THE FOLLOWING COMPTIA IT FUNDAMENTALS EXAM OBJECTIVES ARE COVERED IN THIS CHAPTER:

• 5.5 Describe the importance and impact of various environmental and safety concepts
  • Proper disposal methods
    • RoHS
    • CRT monitors
    • Scanners
    • Batteries
    • Ink/toner
    • Hard drives
  • Power
    • Energy efficient devices
    • Power profiles
      • Power options
      • Sleep/hibernation
    • UPS vs. surge protector vs. power strip
      • Power limitations
    • International power differences
    • Device placement
      • Airflow
      • Humidity
      • Temperature
      • Dust accumulation
      • EMI
    • Electrostatic discharge concepts
    • Ergonomic concepts
      • Proper keyboard and mouse placement
      • Sitting positions
      • Monitor level placement
    • Follow manufacturer safety guidelines

The environment and safety might, at first glance, seem like strange topics for a book on IT fundamentals. We're talking about computers here, right? In reality, computers can have a big impact on the environment—many of the components contain environmentally unfriendly or toxic materials. The goal is to minimize the negative impact that computers could have on our surroundings.

Safety is also a valid concern and it can take several forms. Granted, it's not like working with computers is as dangerous as being a firefighter or a chef (flames and knives, what could go wrong?) or several other professions, but there are still things to watch out for. Your own personal safety and health can be affected by using poor posture for hours on end while working with a computer. Computers use electricity, and if you're not careful you could get hurt or even possibly killed. (The odds of dying are very small provided that you are careful!) There's also the safety of your components. Treating them the right way extends their lives. Doing things like immersing your laptop in water will result in more frequent hardware purchases.

So even though the environment and safety aren't likely to be the two topics at the top of your mind when you think about computers, they are important factors to be aware of. This chapter will teach you about concepts related to safety—both yours and your hardware's—as well as how to properly dispose of items to not damage the environment.

Safe Interactions with Computers

Working with computers isn't as unsafe as many other jobs out there, but there are still potential ways to hurt yourself or others by using computers. One of the most important things you can do is to always follow the manufacturer's safety guidelines. This is true for all computer components, but it's especially true when working with potentially hazardous materials such as CRT monitors, batteries, and toner. Some safety guidelines are relatively simple and common-sense, while others are critical and prevent serious injuries or death.

Over the next several sections, I will share concepts related to safe interactions with computers. I will start with a discussion on ergonomics, which is about your own personal safety and health. Next, I'll talk about power and electricity—as you know, electricity can kill you if you're not careful! After that, I will cover the safety of your computers and components such as how to clean them properly and where they should be placed for optimal health. Finally, I will talk about environmental safety and how to properly dispose of your old computer equipment.

Using Proper Ergonomics

Ergonomics is the study of people's efficiency in their working environment. Many people have bad posture or typing form when using computers, which can result in headaches, neck problems, back problems, strain on shoulder and arm muscles and joints, and repetitive stress injuries such as carpal tunnel syndrome.

If you work in an office, look around at your co-workers. Who is sitting with proper posture and device positioning like what's shown in Figure 12.1?

FIGURE 12.1 Proper ergonomic positions

It's probably not many. Some people don't know what proper mechanics are, and others might know but have fallen into bad habits. In either case, those people are damaging their bodies by not following a few basic principles. Here are the guidelines to follow:

Sit straight with your feet flat on the floor. This might sound like what your teachers told you when you were young, but it's good advice. Your upper body should be at a 90–120 degree angle to your thighs, which should be parallel to the floor. Or, your hips can be slightly above your knees. You should have support of your lower back (lumbar) area. Try to distribute the pressure on your seat evenly, make sure the area behind your knee is not touching the chair. Adjust your seat so it's low enough for you to have your feet flat on the floor or on a footrest.

Keep your elbows relaxed at your side and at 90 degrees. Your keyboard and mouse should be placed in such a way that there is minimal to no bend in your wrists, and your elbows are at a 90 degree angle. Some people find it easier to use an ergonomic keyboard and mouse (covered in Chapter 2, “Peripherals and Connectors”). The keyboard and mouse should be directly between you and your monitor, at or slightly below your elbow height, and close to each other to minimize reaching.

Look straight at your monitor. The top of your monitor screen should be parallel to or slightly lower than your eyes. Looking up at your monitor will cause undue neck strain. In addition, the screen should be approximately 19 to 24″ from your eyes. (Some resources say up to 28″, or roughly arm's length away.)

And here are a few more tips:

• Use a headset if you are on the phone. Don't cradle the phone between your head and your shoulder.
• Use a document holder to keep paper documents you need to see at eye level, so you don't have to look down at them.
• Take periodic breaks, every 30 minutes or so, to get up and stretch! Even if it's just for 15–30 seconds, it greatly helps your circulation and keeps you more alert.

Many companies offer their employees free ergonomic assessments as part of their benefits packages. An ergonomics expert can come and assess your workplace and make suggestions on how to improve your positioning. Many of the same companies will also pay for ergonomic chairs, desks, or computer accessories for employees who need them. Exercise 12.1 will show you how to assess ergonomics. You can do this on yourself or on a co-worker. Just warn the other person first before doing it!

Understanding Power and Electricity

Computers need power to operate, and they're actually rather particular about the power they need. Too much or too little and the computer won't work or may sustain permanent damage. Unintended electricity from the wrong sources—the obvious one being electrical storms, but the un-obvious one being people improperly touching components—can also result in fried parts.

The other aspect to understanding power and electricity is to know how your computer, whether it be the hardware or the operating system, can help the computer conserve electricity or power. For a desktop, this can mean monetary energy savings. For a laptop, it can mean the difference between a two-hour battery life and a six-hour one. This section will look at various power and electricity concepts in depth.

International Power Differences

Computer components require direct current (DC) power, whereas the electrical power systems across the world provide alternating current (AC). The computer's power supply is the conduit between the electricity coming from a wall outlet and the system itself, and it converts AC to DC. For laptop computers, the power adapter provides the same functionality. The only difference is that laptops have an attached battery that can store electricity for use when the system is not plugged into the wall. Smaller portable devices rely solely on an internal battery, which gets charged through an adapter that plugs into an electrical outlet as well. As you can see, there's a common theme developing here, and it's that all computer devices plug into an outlet at some point. The question is, what kind of outlet is it? It depends on where you live.

In the United States, the power grid supplies 120 volts AC. In Europe, China, and many other parts of the world, the power grid supplies from 220 to 240 volts AC. The adapter's prongs to plug into the wall outlet are different enough that you can't plug a device intended for one range into an outlet for the other, but if you were able to, it could have disastrous consequences—the very least of which are fried components.

Most computer power supplies have a switch on the back like what you see in the dusty image in Figure 12.2. (Reminder: clean the dust from your power supply fans!) This switch is red, and it might be hard to read, but on the right side it says 115. Options will be 110 and 220, 115 and 230, or 120 and 240. If you're in the United States and you set the switch to the 220–240 range, the power supply will expect more voltage than what it will receive, and it probably won't power up. If you are in a country with higher voltage and you select the 110–120 setting, the power supply will get overloaded. You will surely fry the components, and it's possible the power supply could catch on fire.

FIGURE 12.2 Power supply voltage switch

Maintaining Power

Most people realize that when a computer is plugged into a wall, having too much power (a power surge) is a bad thing because it can fry electronic components. Having too little power, such as when a blackout occurs, can also wreak havoc on electrical circuits.

Power strips come in all shapes and sizes and are convenient for plugging multiple devices into one wall outlet. This solves the problem of having a computer, monitor, printer, speakers, and other peripherals that require a power outlet, but only two plugs in the wall outlet. Most power strips even have an on/off switch so you can turn all of the devices on or off at the same time. A simple British power strip is shown in Figure 12.3. It has switches for each individual outlet as well as a power light.

FIGURE 12.3 A power strip

Don't make the mistake of thinking that power strips will protect you from electrical surges, though. Power strips are nothing but glorified extension cords. If you get a strong power surge through one of these devices, the strip and everything plugged into it can be fried. Some people like to call power strips “surge protectors” or “surge suppressors,” but power strips do nothing to protect or suppress.

Devices that actually attempt to keep power surges at bay are called surge protectors. They often look just like a power strip so it's easy to mistake them for each other, but protectors are more expensive, usually starting in the $25 range. They have a fuse inside them that is designed to blow if it receives too much current and not transfer the current to the devices plugged into it. Surge protectors may also have plug-ins for RJ-11 (phone), RJ-45 (Ethernet), and BNC (coaxial cable) connectors as well. Figure 12.4 shows a surge protector.

FIGURE 12.4 Surge protector

The best device for power protection is called an uninterruptible power supply (UPS). These devices can be as small as a brick, like the one in Figure 12.5, or as large as an entire server rack. Some just have a few indicator lights, while others have LCD displays that show status and menus and come with their own management software. The back of the UPS will have several power plugs. It might divide the plugs such that a few of them provide surge protection only, whereas others provide surge protection as well as backup power, as shown in Figure 12.6.

FIGURE 12.5 An uninterruptible power supply

FIGURE 12.6 The back of an uninterruptible power supply

Inside the UPS are one or more batteries and fuses. Much like a surge suppressor, a UPS is designed to protect everything that's plugged into it from power surges. UPSs are also designed to protect against power sags and even power outages. Energy is stored in the batteries, and if the power fails, the batteries can power the computer for a period of time so the administrator can then safely power it down. Many UPSs and operating systems will also work together to automatically (and safely) power down a system that gets switched to UPS power. These types of devices may be overkill for Uncle Bob's machine at home, but they're critically important fixtures in server rooms.

The UPS should be checked periodically to make sure its battery is operational. Most UPSs have a test button you can press to simulate a power outage. You will find that batteries wear out over time, and you should replace the battery in the UPS every couple of years to keep the UPS dependable.

Electrostatic Discharge

Electrostatic discharge (ESD) is the most common culprit for ruined PC parts, although many people have never heard of it. ESD is really just static electricity, the same thing that can shock a person on a low-humidity day.

ESD occurs when two items of unequal voltage potential come into contact with one another. The item with the higher charge passes electricity to the one with the lower charge to even out the voltage. As an analogy, picture two bodies of water meeting; if one has a higher level, water will flow quickly into the other one until they're the same. In the case of electricity, the equalization happens so fast that the item of lower charge receives a rush of electricity that feels like a shock. You've experienced ESD firsthand if you've ever scuffed your socks on the carpet and then touched someone, giving the person a shock. You were not shocked yourself because, in that case, you were the item of higher charge.

Whereas voltage (measured in volts) is the difference in electrical charge, current is the rate at which electrical charge flows and is measured in amps. ESD is a high-voltage shock (3,000 volts or so), but it doesn't harm a person because it has very low current. The human body doesn't draw electricity very strongly; it merely draws enough to equalize the charge and then stops. To damage a human body, there must be sufficient amps as well as volts. That is why a 110-volt wall outlet can hurt a person more than a 3,000-volt static electricity shock—the static electricity shock has low amperage.

Electronic equipment, though, is extremely sensitive to damage by high voltage, even when the amperage is very low. Humans notice ESD only when it reaches 3,000 volts or so, but ESD can damage a circuit board with less than 300 volts. (Some experts say as little as one volt is enough to do some damage.) This means that a person could touch a circuit board and destroy it with static electricity without even noticing. The next time they tried to use that circuit board it would be dead, and they would have no idea why. Furthermore, ESD damage doesn't always show up immediately. It may cause the device to malfunction, or it may weaken the device to the point that it fails a week or a month later.

Generally speaking, any exposed circuit boards are targets for ESD damage, especially motherboards. Also at risk are microchips both on and off those boards, particularly RAM and ROM. Devices not very susceptible to ESD damage include those in which circuit boards are never exposed, such as keyboards, mice, speakers, monitors, and printers, and those that don't contain circuit boards.

If you never open your computer's case, the risks of harming it via ESD are very low. If you have to work inside a computer for some reason, such as to install a new circuit board or more RAM, here are some tips:

1. Be aware of the clothing you wear when working inside a PC. Synthetic materials such as nylon generate much more ESD than natural fibers like cotton and wool, so dress in natural fabrics. Avoid working in stocking feet—wear rubber-soled shoes.
2. Keeping the humidity high in the work area can also help considerably. The ideal humidity for working on PC hardware is 40 to 80 percent but preferably right around 50 percent.
3. The work surface can also make a difference. Try not to work in a carpeted area; tile or linoleum is preferred. Carpet, especially nylon carpet, tends to generate ESD the same way that nylon clothing does.
4. Grounding both the person and equipment can eliminate ESD risk, because any ESD that builds up can bleed off to the ground harmlessly. To ground yourself, wear an antistatic wrist strap as you work (see Figure 12.7). At your end of the strap is a Velcro bracelet containing a diode that fits against your skin. At the other end is an alligator clip that you attach to the grounding pin on an electrical outlet (the round, third hole) or to some other grounding source. If no grounding source is available, attach the clip to the PC's metal frame. For maximum ESD prevention, wear an antistatic wrist strap whenever you're working on a PC with the cover off, especially when handling circuit boards.

FIGURE 12.7 An antistatic wrist strap

Another way to minimize ESD risks is to touch the metal frame or power supply of the PC frequently as you work. Doing so doesn't ground you, but it does equalize the electrical charge between you and the PC so there is no difference in potential between you and the components you touch. Do this every few minutes to make sure no build-up occurs.

Antistatic mats are also available. These sit on the work surface and perform the same function for the parts on which you're working as the wrist strap does; the mat has a cord that attaches to the ground pin on an outlet.

Whenever transporting components, use an antistatic plastic bag. These bags are usually pink or gray and have a coating that collects static charge on the outside of the bag, keeping it away from what's inside the bag. Expensive circuit boards should always be stored in an antistatic bag when not in use. Computer stores sell extra bags, but most people accumulate a collection of them simply from buying and installing new hardware.

Finally, you can buy antistatic spray that minimizes static charge in your environment. This is usually a colorless, odorless liquid in a pump bottle that you spray on the carpet and on your clothing.

The flipside of the ESD conversation isn't about how you can hurt computer components, but how they can hurt you. For the most part, working inside a computer case is pretty safe. You have to watch out for sharp metal edges, but as long as the computer is powered off when you are working on it, you should generally be fine. There are two notable exceptions though—the inside of power supplies and CRT monitors.

CRT monitors and power supplies contain capacitors, which store electricity. They can store electricity for years, even when unplugged from a power source. Touching a full capacitor can cause it to release its energy through you at very high amperage, which could kill you. Capacitors need to be drained by a trained professional using a high-voltage probe. The moral of the story is to never open the back of a CRT monitor or the case surrounding a power supply.

Energy-Efficient Personal Computing

Saving energy is not only good for the environment but good for your wallet as well. A computer's operating system can help save energy by powering off devices that are not actively in use or by suspending power to the system or monitor during periods of inactivity. In addition, some hardware devices are specifically designed to consume lower levels of power, which is a good thing. In the following sections, you'll learn how to minimize the amount of power your computers use while impacting your productivity as little as possible.

Power-Management Plans

Most systems have built-in power-management features that enable you to save energy by shutting down the computer or by placing it in a low-power mode after a specified period of inactivity. The operating system typically controls power management, but some systems also have power-management features available via BIOS Setup.

LOW-POWER MODES

Different OSs call the various modes by different names, but here are the basic modes. You can set the OS to put the PC into one of these modes automatically after a specified period of inactivity:

Sleep/Standby All components of the PC except RAM are powered down so that the computer uses only the tiny amount of power required to keep the RAM's content alive. When you resume, all the devices are powered on again. Because the content of RAM remains, waking up from this mode is nearly instantaneous. In Windows and Mac OS, this is called Sleep mode; in Linux it's called Suspend to RAM.

Hibernate The content of RAM is copied to a special holding area on the hard disk, and then the system is powered off completely, including the RAM. When you resume, the previous RAM content is copied back into RAM, and all the devices are powered on again. Waking from this mode takes a little longer (up to 1 minute), but that's less time than it would take to start up the computer completely after it's been off. In Windows, this feature is called Hibernate or Hybrid Sleep. On Linux, it's called Suspend to Disk. On a Mac, the Safe Sleep mode copies the contents of RAM to the hard disk before sleeping, so that if the battery runs out and the computer loses RAM power, hibernation automatically is in effect.

In addition, some OSs enable you to specify a time period of inactivity after which the display dims or turns off completely, and the hard disk stops spinning its platters (if it's a mechanical hard disk, rather than solid state). Exercise 12.2 gives you practice putting a computer to sleep.

CHOOSING POWER-MANAGEMENT SETTINGS

Some companies have energy-saving policies, which dictate that employees must place their computers in a low-power mode, or turn them off completely, at the end of a workday. Even if your company doesn't have an official policy, you may want to create one for yourself.

You can do this in your OS by setting up a power plan. A power plan tells the computer to shut down or to go into one of the power-saving modes from the previous section after a specified period of inactivity. If it's a notebook computer, you can choose separate settings for when it's on battery power versus when it's plugged in. Windows, Mac OS X, and Linux all have similar power-management features.

In Windows, you can choose a standard power plan that includes settings for the display, the hard disks, and the amount of time before the computer goes to sleep. After choosing a plan, you can then customize that plan in a variety of ways, as you'll see in Exercise 12.3.

Mac OS X has an additional power-management feature: it enables you to set the computer to start up and shut down at a certain time every day (see Figure 12.8). In System Preferences, click the Energy Saver icon, which looks like a light bulb. Then, on the Energy Saver screen, click the Schedule button.

FIGURE 12.8 Configuring a Mac to shut down or start up at a certain time

Power-Conserving Equipment

In addition to the OS settings for conserving power, some hardware devices also have their own power savings. For example, notebook PCs use less power than desktops, so replacing as many desktops as possible with notebooks can save a company a significant amount of power. The following sections cover some other component savings you can achieve.

MONITORS AND ENERGY SAVINGS

The computer display, whether it's built into your notebook computer or a separate standalone monitor connected to a desktop PC, consumes the most power of any component in an average system. CRTs consume more power than LCDs, so one way you can conserve energy is to switch over to LCDs for as many computers as possible.

Another way to conserve power is to decrease the brightness of the monitor. Especially on an LCD, doing this can make a big difference; the brighter the display, the more light it generates, and more light means more power.

You can change screen brightness in several ways. One is via the power plan in the OS. This is configured via the Power Options app in Control Panel. You can also manually adjust a monitor's brightness. On a stand-alone monitor, there are typically buttons that open a menu system onscreen from which you can control brightness along with many other factors. On a notebook display, there is usually a brightness control associated with one or more of the keyboard keys plus the Fn key. Hold down Fn, and press the key that is associated with Increase Brightness or Decrease Brightness.

HARD DRIVES AND ENERGY SAVINGS

Some hard drives are more energy-efficient to operate than others. Solid-state drives, for example, have much lower power needs because there are no mechanical parts. Unless there is a read-write operation, they consume no power. Among mechanical hard disks, drives with lower rotational speeds sometimes use less power than their high-performance counterparts, although the age of the drive is also a factor; newer hard drives use newer technologies that make them more efficient.

ENERGY STAR

Originating in the United States, the Environmental Protection Agency Energy Star rating system for computer technology is now recognized internationally; many other nations use the standard as part of their own power-reduction policies. When you see the Energy Star logo on a PC or a component, as shown in Figure 12.10, you can assume that the device meets certain energy-efficiency standards. For example, an Energy Star monitor puts itself into standby (a low-power mode) when it doesn't detect a signal from the PC, and Energy Star laptops are able to go into Sleep or Hibernate mode when the lid is shut. Energy Star also applies to motherboards, power supplies, and BIOSs that are able to manage power consumption.

FIGURE 12.10 Energy Star logo

Practicing Good Device Care and Placement

Preventive maintenance is an important part of computer usage. This can include backing up files, preventing damage from electrical surges and static electricity, and cleaning the computer. Cleaning the computer regularly and placing devices in a good setting to ensure proper performance will extend the life of its components. This helps your budget as well as the environment.

Cleaning a Computer

Computers that are cleaned regularly are not only more pleasant to use but also can last longer. Dirt, clumps of debris, and other accumulation can make components run hotter, shortening their lives. In the following sections, you'll learn about some of the cleaning products available for cleaning a computer inside and out. You'll also study some techniques for cleaning various areas without damaging them.

Cleaning Supplies

Expensive cleaning supplies aren't required to clean a PC, but neither should you use whatever products happen to be lying around. Here is a list of basic supplies to have on hand:

• A spray cleaning product designed for plastics, preferably one designed for computers. The ones designed for computers often have antistatic properties that regular cleaners lack.
• A monitor cleaner, either spray or towelette, designed specifically for cleaning monitors or other electronics screens (like televisions). Don't use a glass-cleaning product that contains ammonia because ammonia can destroy the antiglare coating on some monitors.
• A can of compressed air for blowing dust out of crevices.
• Cotton swabs.
• Denatured isopropyl alcohol (not rubbing alcohol, because that has too much water in it).
• An antistatic spray designed for computer work areas.
• (Optional) A small handheld vacuum cleaner designed for electronics. (Don't use a regular vacuum cleaner because the filter isn't fine enough and because a regular vacuum can generate static electricity that can harm equipment.)

Cleaning a Monitor

Always turn a monitor off before cleaning it. If any liquid gets inside, the monitor can air dry without worries of short-circuiting. It's also much easier to see dirt and spots on the screen when it's dark.

First, clean the outer casing with a spray computer-cleaning solution. Spray the cleaner on the cloth, not directly on the casing, to avoid spraying into vent holes.

Next, clean the glass using a cleaner designed specifically for monitors. This can be in the form of a spray or a towelette. Don't use ordinary cleaning products on monitors because they can leave streaks and sometimes harm the antiglare coating. Don't use regular glass cleaner either, because it contains ammonia, which can also harm the surface. Don't spray the screen directly, because the liquid may drip down below the bottom bezel; spray a cloth and then wipe the screen.

Cleaning External Surfaces

As with monitors, clean the outside casing of PCs, printers, scanners, and similar equipment with a computer-cleaning spray product. Mild general-purpose spray cleaners also work. You can also use mild soapy water and a damp cloth (not soaking wet) to clean external surfaces only—nothing internal or with a vent or crack that leads inside.

Cleaning a Keyboard

Because it's always at the forefront of activity, the keyboard can get very dirty. Although technicians may remind end users to keep their computing areas clean, more often than not people neglect to do so. They may type with unwashed hands or eat, drink, or even play with their pets while they work. All this activity leaves dirt, oil, and other residue on the keyboard.

To clean a keyboard, first turn off the PC. The keyboard need not be unplugged from the PC. Then, turn the keyboard upside down and shake it or tap it (it's called burping a keyboard) to remove any loose debris. Or, hold it over a trashcan and spray beneath the keys with compressed air. What falls out—and the amount of it—is often surprising!

Use a cloth dampened with a spray cleaning solution designed for PCs, or a towelette containing a PC cleaning product, to clean all visible surfaces. Get down between the cracks with a cotton swab or a bit of folded paper towel. Removing the keys isn't recommended because it can be difficult to get them back on again. If you have access to one, a small handheld vacuum cleaner designed specifically for working with electronics can be useful in sucking debris out from under the keys.

If liquid is spilled onto a keyboard, turn the keyboard upside down and unplug it immediately from the PC (if possible), or turn off the PC. Turn the keyboard upside down to release as much of the liquid as possible, and then let it dry for at least 48 hours. If the liquid was plain water, the keyboard will probably be fine after it dries; just clean the outside as well as possible. But if the liquid contained sugar, the keyboard may never be completely clean again. Some people have successfully cleaned sticky keyboards (the separate kind, not those found on a notebook PC) in a dishwasher. To try this (there is little to lose with a keyboard that is otherwise on its way to the trash can), place the keyboard on the upper rack, wash it without using the heat-dry feature and with very little or no detergent, remove it after the wash, rinse it, and set it in a dish drainer for several days to dry out.

Cleaning a Mouse

A mouse, like a keyboard, gets very dirty because it's constantly being handled. In addition, older mechanical mice have the added feature of the ball on the bottom, which rolls across the desk picking up dirt and lint and moving it inside the mouse. As a result, the rollers and sensors on a mechanical mouse can become encrusted with dirt rather quickly, causing the mouse to malfunction. An optical mouse has fewer problems with dirt inside, but dust and hair can still accumulate at the opening where the light shines through.

When a mouse is dirty, the pointer on-screen may jump or stutter, or moving the mouse in one direction may result in no action at all. In addition, the mouse may become more difficult to roll.

To clean a mouse, first wipe off the outside with mild soapy water or cleaning product designed for computers. Then turn the mouse on its back. If it's an optical mouse, use a cotton swab dipped in denatured alcohol to clean out the hollow area where the light shines through if there is any debris inside. (Alcohol dries quickly, so it's used instead of water anytime you clean internal areas of electronics.)

If it's a mechanical mouse, rotate the plastic plate that holds the ball in place. Then turn the mouse over again, and the ball and plate should fall into your hand. Clean inside the ball's chamber with alcohol on a cotton swab. Clean the ball itself with mild soapy water, and dry it thoroughly. (Don't use alcohol on a rubber ball because it dries the rubber and makes it brittle.)

Cleaning the Inside of a PC

A desktop PC should be cleaned out regularly—at least once a year. Its cooling and ventilation fans suck in a lot of air, and with that air come pollutants that can build up over time. Even a thin layer of dust on a circuit board can make it run hotter, shortening its life, and clumps of dirt and hair can prevent the free flow of air through the case.

Remove the cover from the case (following the directions that came with it on how to do so). Inside a desktop PC there may be big clumps of hair and dirt; fish these out by hand and throw them away. Then check the motherboard and expansion boards for dust accumulation, and blow it out with compressed air. If it's been a long time since the PC has been cleaned, you may want to take it outside or to an open area so you don't blow dust all over someone's work area. The motherboard doesn't have to be sparkling clean; it just needs to have the major clumps of visible debris removed. A handheld vacuum cleaner designed for electronics can come in handy if available.

To clean anything that involves circuit boards or chips, stay away from liquids, especially water, because of the danger of short-circuiting if the board isn't completely dry when the PC powers up. If some kind of moisture is absolutely necessary, use alcohol on a cotton swab.

Old circuit boards can build up deposits on the metal pins (contacts) along the edge; you can remove these deposits with a pencil eraser or with alcohol and a cotton swab. Avoid touching any of the circuitry, chips, or transistors on a circuit board; it's easy to damage them. Handle circuit boards only by the edges.

Other parts that tend to accumulate dust include the fan on the power supply, the fan on the processor, and the air vents in the case. Wipe off the case's air vents with a damp paper towel. For the power supply, point the compressed air nozzle at an angle to the fan opening rather than blowing straight down into it to avoid driving the dirt even deeper into the power supply box instead of blowing it out. Exercise 12.4 walks you through cleaning a desktop computer.

Notebook PCs and all-in-ones also need to be cleaned out periodically, although not as often as desktops because there is less airflow in them and the vents are smaller, so less debris tends to accumulate. Non-desktop models are often harder to get into; you may need to obtain instructions from a service manual to know which screws to remove to open one and access its inner spaces where dust and dirt may have accumulated.

Cleaning a Printer and Replacing Consumables

All types of printers can be cleaned on the outside with a cloth dampened with a spray cleaner for PCs. This won't make the printer perform any better, but it will make for a nicer working environment.

The only parts inside an inkjet printer that need cleaning are the inkjets, and these aren't cleaned by hand—a utility built into the printer cleans them. The ink in an inkjet printer is liquid; if the printer isn't in frequent use, the ink dries out and bits of dried ink remain in the nozzles. The cleaning procedure flushes out any dried-up ink. It uses some ink to do so, so don't clean the inkjets unless the print quality has declined.

On most inkjet printers, there are two ways to activate the cleaning utility: pressing a sequence of buttons on the printer itself or using the cleaning utility in the printer's software. For example, Figure 12.11 shows the Clean Printhead option on an HP inkjet printer; there are also commands for aligning print cartridges and printing test pages.

FIGURE 12.11 Menu options on an HP inkjet printer

Laser printers use toner rather than ink. Because toner is a dry substance (a mixture of plastic resin and iron oxide), it doesn't clog things the way liquid ink does. However, toner is a loose powder that can scatter over clothing and the work area if the cartridges aren't handled with care. Clean up any spilled toner with a vacuum designed for electronics or with a damp paper towel. If it gets on clothing, you can get it out with a magnet, because toner is half iron. Don't use a regular vacuum cleaner: general-use vacuums don't have fine enough filters, so the toner particles can pass through them and get into the air where they become a health hazard to breathe.

Several specific parts of a laser printer can accumulate toner, making them less effective over time. Depending on the age and model of the printer, though, these parts may or may not be reachable. Consult the manual that came with the printer to find out what you can do to clean your laser printer. Always be careful inside a laser printer as there are components hot enough to burn you or give you an electric shock.

Consumables is another name for the ink or toner cartridges in a printer, the paper, and any other parts that regularly must be replaced, such as a felt cleaning pad on some models of laser printers.

Each printer has a specific procedure for replacing consumables; follow the instructions for your model. Here are some general tips, though:

Inkjet Tips

• On an inkjet printer, the printer will tell you when it's low on ink or completely out. You may also notice degradation in image quality or a missing, faded, or striped color on some printouts.
• The printer may have a sequence of buttons you have to press to bring the ink cartridge into view where it's accessible, or the cartridge may move into an accessible position when you open the lid.
• There is usually a lever or button you press to release the old cartridge. Then it slides out of a groove or socket.
• Unwrap the new cartridge, and remove the piece of tape that is covering the metal contacts on the bottom of the cartridge. Insert it firmly into the socket in the same orientation as the one you removed. Then close the printer.
• The printer may ask you to print a test page or to clean or align the print heads. Do whatever it suggests. Check the manual as needed.

Laser Tips

• On a laser printer, the printer will indicate when it's getting low on toner. At this point, you may be able to get a bit of extra life out of the cartridge by taking it out and shaking it gently from side to side. Don't turn it upside down or tilt it, or toner may fall out. Handle it very gently.
• A new toner cartridge may have multiple pieces of tape or plastic guards on it to prevent toner leakage. Make sure you remove them all before inserting the cartridge.
• The printer may recognize the new toner cartridge immediately, or you may have to use the printer's menu system to let it know that it has new toner.

Both ink and toner cartridges can be recycled. Recycling companies often offer free shipping bags that you can use to send in your used cartridges. Some companies even pay you (a small amount) for empty toner cartridges.

Cleaning Removable Media

Disc drives that read removable media like CDs and DVDs don't usually require any cleaning. The discs themselves, however, can sometimes become dirty or damaged such that they won't play properly without some rehab. To remove fingerprints, buff them off gently with a soft cloth. If the surface is grimy or sticky, use an alcohol-dampened towelette or cloth, and air-dry the disc thoroughly before use.

Is the problem more than just a few fingerprints? Some scratches on a disc can be minimized by using a scratch-remover kit, to the point that the disc is made readable. These kits are available for home use, and you can easily find them for purchase online.

Proper Device Placement

Computers are fairly sturdy, but they are susceptible to a few risks. Some of the more apparent ones are water and electrical shock, but heat, humidity, dust, dirt, and other issues can harm them as well. Some basic common sense can go a long way toward mitigating any risks, and that includes placing computers in an area that allows for optimal performance. In the following sections, you'll learn some placement principles to keep a computer physically safe and healthy.

Checking the Weather Forecast

PCs generate a lot of heat when they operate; cooling fans and heat sinks help channel the heat away. The cooler the room in which the PC sits, the easier it is for those components to stay cool. Don't make the room too cool, though, because at very low temperatures (below freezing), frost build-up can become an issue. The heat from the PC melts the frost, which creates water, and with water comes the possibility of short-circuiting. Ideally, computers will operate in room temperatures or slightly cooler environments.

In the past, computers were more sensitive to temperature than they are today. At one time it was common to find a computer room at a corporate headquarters where a raised floor kept cool air circulating, where the air conditioning was on high, and where employees dressed warmly all year round. Today these huge computers have mostly been replaced by ordinary-looking PCs that don't require any special temperature treatment. The main reason PC cooling requirements are now less stringent is that today's CPUs run at much lower voltages. Still, it pays to remember that PCs like the cold more than people do. If the people are cold, the PC is probably comfortable. If the people are hot, the PC is probably very hot.

Storage temperature for PC components is less of an issue than operating temperature, but extremes still must be avoided. Don't store your PC in an unheated shed in a cold climate all winter, and don't leave it baking in the back seat of a car in the summer months. When you bring a PC inside after it has been very cold or very hot, let it sit until its temperature is the same as that of the room before turning it on. This is especially important when bringing it in from the cold, because condensation can create dampness inside the PC.

Computers subjected to ultra-hot temperatures, such as in building fires, will probably not work anymore because plastic parts will have melted. However, the hard disk might still have recoverable data. Try connecting the hard disk to another computer to see if it is readable. If it contains very important data and can't be read normally, a data-recovery service may be able to help (although not cheaply).

Along with the temperature, remember to mind the humidity. If the humidity is too high, you run the risk of developing condensation. If it's too low, then ESD will be prevalent. The ideal humidity is around 50 percent, but you should be okay in the 40–80 percent range.

Ensuring Proper Airflow

Proper airflow around a computer helps it stay cool. The exhaust fans can expel hot air from inside the case, and the intake vents will bring in cooler air. The ideal location for computers is in an open environment where they can breathe and stay cool. Some computer desks have convenient cubbyholes to put computers in—those are a bad idea. Enclosed or confined spaces don't let air circulate well, which will make the computer run hotter than it should.

There is one necessary evil that comes with placement in an open area, and that is dust accumulation. Dust is almost everywhere, whether you can see it or not. And having the computer constantly suck in air and push it back out through exhaust fans means that dust comes with the territory. If dust accumulates on components, they will trap heat more efficiently (not a good thing) and therefore heat up quicker. Dust is also electrically charged, meaning that dusty areas are more prone to ESD. The solution is to periodically open the case and clean out the dust, as discussed earlier in this chapter.

Avoiding Electromagnetic Interference

Electromagnetic interference (EMI) is caused when electricity passing nearby generates a magnetic field that interferes with the operation of a cable or device. Another name for this is crosstalk. It occurs only when the PC is on, and it goes away when the PC is off. It causes no permanent damage (usually) but can cause data loss if the affected cable is transporting data. EMI affects only copper cables, not fiber-optic ones.

EMI can come from unshielded cables, high-voltage power lines, radio transmitters, motors (even those on refrigerator compressors), microwave ovens, cordless phones, fluorescent lights, and other sources. Electricity passing through a wire generates a magnetic field, and magnetic fields generate electricity. Most computer cables move data via electrical pulses, so a changing magnetic field builds up around the cable. When one cable runs next to another, each cable's changing magnetic field can interfere with the data being sent along the other cable. Why? Because changing magnetic fields generate electricity, and the pattern of electricity through the cable is what forms the data being sent. When that pattern is altered, the data can become corrupted.

EMI may be a problem when a data cable isn't carrying its data reliably to its destination. For example, perhaps a printer is printing garbage characters interspersed with the normal characters, or perhaps a network connection keeps timing out due to transmission errors. Power cables can also be susceptible to EMI; this can manifest itself as a power fluctuation. Power fluctuations, in turn, can cause lasting damage to equipment, so in that sense EMI is capable of causing permanent damage.

One way to avoid EMI problems from unshielded cables is simply not to run any cables next to one another and not to allow a cable to be placed near any other cable. This isn't often practical, though, because most computer users have a tangle of cables behind their PCs going in many directions. More specifically, avoid running network cables and power cables next to each other. If you do have EMI issues, troubleshoot them as they occur by selectively moving cables that seem to be having problems.

Another way to minimize EMI is to select the proper cables to begin with. Shorter cables are less prone to EMI than longer ones, so use the shortest cable that will do the job. Many cables sold these days are shielded, which means they have a special wrapping that minimizes EMI interference. Buying shielded cables, although more expensive, can help greatly with EMI problems. EMI problems caused by external sources, such as power lines, can be difficult to solve; sometimes moving the devices to a different area in the room or building can help.

Surveying for Other Dangers

Temperature, humidity, airflow, dust, and EMI can all pose dangers to computers, but there are other threats out there as well. Some of the main categories include liquids, magnets, and physical damage.

LIQUIDS

Water and electronics don't mix. Do whatever you can to keep water away from your computer. This includes not setting beverages near the computer where they can be knocked over into it, not setting cold items on an air vent that may drip water from condensation into the PC, and not spraying liquid cleaning products directly onto the PC, especially anywhere near its air vents.

A computer damaged by flooding or submersion in water may be beyond repair, but to maximize the chances of recovering some of the data, you should disassemble the computer and dry the pieces out thoroughly, and then reassemble it before attempting to turn it on. Any water left in crevices can cause a short circuit, ruining whatever is left of the computer's functionality.

MAGNETS

Magnets and computers don't mix. You learned in the discussion of EMI that changing magnetic fields generate electricity. A magnet can create an electrical charge in a component just by being near it, and that charge can harm the component or cause data corruption in magnetic storage devices such as hard disks. For this reason, you shouldn't use magnetic screwdrivers or other magnetized tools inside a PC. Toolkits designed for use with electronics are non-magnetized.

PHYSICAL TRAUMA

Computers aren't highly susceptible to physical trauma, but it's always best to handle them with reasonable care. Everyday bumps like inadvertently kicking a PC that is sitting on the floor probably won't cause any problems, but knocking a PC off a table while it's running can cause some damage.

There are two reasons why physical trauma is bad for a PC. One is that it causes parts to come loose. If someone drops a bare circuit board and it hits the floor just right, a wire connecting a chip or resistor to the board can come undone, or some solder can be knocked off. Most people don't have the skill to repair a circuit board, so a board with a broken connection is basically ruined. Connectors inside a PC can come loose as well. For example, the cables that connect drives to the motherboard can work loose, as can power supply plugs to drives. Circuit boards can also pop out of expansion slots, and chips can pop out of their sockets.

The other reason to avoid physical trauma pertains specifically to magnetic hard disks. A hard disk has read/write heads that skim just above the surface of the drive. When the drive is subjected to physical trauma, those heads can bounce, scratching the surface of the drive and causing disk errors. The risk of this type of damage is less when the computer is off because the read/write heads move into a parked position away from any data when the drive powers down.

“Be careful” is the best advice to follow for avoiding physical trauma. Examine your work area for hazards such as cords running across a path where people walk or devices sitting too near the edge of a table. Make any corrections you can to ensure a safer work area. If you accidentally jar a PC so that it stops working, remove the cover and check that all the connections are snug. For a notebook computer, invest in a well-padded carrying case for use whenever you transport it. Exercise 12.5 walks you through checking a work area for potential risks.

Using Proper Disposal Methods

Certain computer components and consumable supplies can pollute the environment if you dispose of them along with your regular trash. That's why, in some countries, laws or guidelines require special disposal techniques for certain items. The laws vary depending on the country and state in which you reside, so it's important to familiarize yourself with what's required in your region. In addition, even if your region doesn't require a certain environmentally friendly disposal technique, you may wish to go the extra mile to help the environment and practice that disposal method anyway. When in doubt, find a recycling center or other authorized disposal company.

Restriction of Hazardous Substances

In 2003, the European Union passed the Restriction of Hazardous Substances (RoHS) Directive, and it took effect in 2006. This directive restricts the use of six hazardous materials in the manufacture of various types of electronic equipment. These six substances are lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ether. (The latter two are flame retardants used in some plastics.) RoHS is closely linked to the Waste Electrical and Electronic Equipment (WEEE) Directive, which sets collection, recycling, and recovery targets for electrical goods.

Consumer electronic components that may be affected by RoHS include just about anything with a circuit board in it, including computers, cell phones, routers, and printers.

RoHS is primarily an issue on which device manufacturers focus; consumers aren't required by law to do anything. However, consumers are strongly encouraged to dispose of items that contain one or more of the six restricted substances by recycling electronic components or delivering them to a hazardous-materials facility rather than discarding them in the trash.

RoHS doesn't require specific product labeling, but many manufacturers have adopted their own compliance marks. Visual indicators may include “RoHS Compliant” labels, green leaves, check marks, and “PB-Free” markings. The WEEE trashcan logo with an X through it is also an indicator that the product may be compliant (see Figure 12.12).

FIGURE 12.12 The WEEE Directive logo

Monitor Disposal

As you learned in Chapter 2, “Peripherals and Connectors,” CRT stands for cathode ray tube; it's the older, boxy type of monitor. LCD monitors have largely replaced CRTs, but there are still CRTs in service that are now reaching the end of their useful lives. Therefore, CRT disposal is a very timely topic.

Along with the glass that can shatter and cause problems and the potentially lethal capacitors, CRTs contain many environmentally harmful chemicals. Older CRTs contained phosphorous as well. Phosphorous is volatile, and it can explode or start a fire when it combines with the oxygen molecules in water. Therefore, in most regions, it's illegal to dispose of a CRT with your regular trash. You must take it to a community recycling or hazardous-waste disposal facility or pay a recycling company to dispose of it for you.

LCD monitors include circuit boards that contain a small amount of lead, and they're treated similarly to desktop PCs in their disposal.

Scanner Disposal

Scanners aren't quite as bad for the environment as monitors are, but they are still pretty bad. They contain a glass screen, like a monitor does, and also chemicals that are hazardous to the environment. By recycling a scanner, it's possible that the glass and metals can be used for the manufacture of other items. Plus, it's less hazardous material sitting in landfills.

Battery Disposal

All batteries contain toxic substances, such as metals, and can contaminate the environment. Wet-cell (lead-acid) batteries, such as those used in cars and boats, are the most environmentally harmful and have the most stringent disposal guidelines. However, dry-cell batteries, such as those used in PCs and other electronics equipment, are also environmentally hazardous. They contain heavy metals such as mercury, lead, cadmium, and nickel, all of which can contaminate the environment when not disposed of properly, and they can release toxic chemicals into the air when incinerated.

Some of the places where batteries are used in PCs include the following:

• Portable computing devices (laptops, phones, and so on)
• Wireless input devices, such as wireless mice and keyboards
• Motherboards
• Uninterruptible power supplies (UPSs)

Most regions have laws requiring retailers that sell certain types of batteries also to collect them for recycling. The exact rules depend on the battery type and the region. For example, the Battery Directive in the EU (2006) regulates the manufacture and disposal of batteries in the EU. These regulations don't require consumers to recycle; they only require retailers to make that option readily available. The same is true in the United States. Consumers aren't required to recycle most batteries, but vendors are required to take them if consumers want to bring them back.

Printer Ink and Toner Disposal

The toner used in laser printers and photocopiers is carcinogenic, so proper disposal of toner is a matter of public safety. Toner cartridges should be returned to the manufacturer or another company that reclaims and recycles them. Handle toner cartridges with some respect to keep the toner from spilling on you and to keep it out of the air where it could enter a person's lungs. (That's why you shouldn't use a regular vacuum cleaner to clean up toner spills—the air filter isn't fine enough to catch the toner particles, so they get back into the air.)

Printer ink cartridges contain some of the same heavy metals mentioned before as are in batteries and CRT monitors. Recycling them is the best way to go as well.

Hard Drives and Other Computer Component Disposal

Working personal computers can often be donated to charitable organizations that recover and restore them so they can be reused by others in your hometown or halfway across the world. Even a nonworking computer can often be repaired to working condition. For that reason, and to protect your privacy, you should erase the data on your hard disk before disposing of a computer.

Nonworking computer parts should be discarded at local recycling or hazardous-waste disposal centers rather than thrown in the trash, because they may contain components that can be reclaimed. For example, circuit boards contain lead solder, and some of them have coin-style batteries as well.

Cleaning-Supply Disposal

Some of the cleaning supplies used on IT equipment can be hazardous to the environment. Most of the really nasty stuff is associated more with the manufacturing of electronics than with its everyday use, but it still pays to be careful.

You should be able to find disposal instructions on the container of any cleaning chemical. There are different rules in different regions, so check the label. For example, in the U.K., the Control of Substances, Hazardous to Health (COSHH) regulations describe how hazardous substances are to be used, stored, and disposed.

Rather than put complete disposal and handling instructions on the packaging, some products refer you to a material safety data sheet (MSDS) on their website. The MSDS explains what hazards are present in the item, and it dictates the proper disposal and handling of the item.

Summary

This chapter covered important environmental and safety concepts related to computers. The intent of the chapter was to provide a good foundation in how to safely interact with a computer, so that no personal injury or harm to the environment occurs. Following all manufacturer safety guidelines is required for proper safety.

The first topic was ergonomics, which is related to how people interact with their computers. Most people don't intend to have bad posture or otherwise damage themselves when they interact with a computer, but in fact that's what most people do. By following good ergonomic principles, such as sitting upright with both feet flat on the floor, people can avoid injury or pain from using a computer.

The second topic was power and electricity. Everyone knows that computers need electricity to operate, but the power needs to be controlled—too much or too little is no good. There are differences between countries in how much power is supplied, and the power supply can be switched to an appropriate setting based on the locale the machine is in. Maintaining the right power is also critical, and UPSs can help protect a system from brownouts or power spikes. ESD can damage computers, even when undetected by people. Energy-efficient devices and settings within an operating system can save energy as well as money.

Third was device care and placement. Preventive maintenance might not seem directly related to safety, but improper maintenance to computer equipment can result in personal injury or harm to computers. It's important to know how to clean equipment to avoid having problems later. Placement is important too, in order to ensure that the computer operates in the right temperature and humidity, gets the right airflow, avoids EMI problems, and stays clear of liquids, magnets, and other physical hazards.

The chapter closed with a discussion on proper disposal methods. Many computer components contain materials that are hazardous to people and the environment and should be disposed of via recycling centers.

Exam Essentials

Understand the proper sitting position for working with a computer. Users should be seated upright or slightly reclined, with both feet flat on the floor or a footrest. The chair should provide lower back (lumbar) support. Arms should be at the sides, with elbows bent approximately 90 degrees.

Understand proper keyboard and mouse placement. The keyboard and mouse should be placed so the user's elbows can be at a 90 degree angle, and there is little or no flex needed in the wrists. The devices should also be close together to avoid reaching.

Know what the proper monitor placement is. The top of the monitor should be eye level or slightly lower. The screen should be at least 18″ from the eyes, up to about arm's length away. Users should be able to look straight ahead or slightly downward at their monitor, not upward.

Understand international differences in power sources. You don't need to memorize the power output of national power grids, but do know that it's different in various countries. For example, the United States has 120V power and most of Europe has 240V power. The power supply on computers has a switch to set it for the region it's used in.

Know what device can help protect computers from power surges or brownouts. Surge protectors and UPSs can help protect against power surges. Only a UPS contains batteries to supply computers with power in the event of a low-power or no-power state.

Understand what ESD is and how to avoid it. Electrostatic discharge is static electricity. It gets released when one object touches an object with a different charge, and it can damage computer components at levels undetectable to humans. Avoid it by maintaining proper levels of humidity and using antistatic wrist straps, mats, and bags.

Know how to conserve energy when using computers. Options include using energy efficient hardware, as well as setting power options within an operating system to power down devices that are inactive.

Know how to properly clean computer components. The proper method depends on the component, but good rules of thumb are to avoid water or anything with harsh chemicals in it.

Understand proper device placement. Ensure that the computer has proper airflow, with around 50 percent humidity and low dust, is kept at room temperature or cooler (but not freezing), and is not near any potential sources of EMI.

Understand proper computer disposal techniques. Computer components often have heavy metals or other materials that are hazardous to the environment. Don't throw components in the trash. Take them to an approved recycling center.

Chapter 12 Lab

Properly disposing of used computer parts is a very important topic, yet it's something that most people don't know how to do. Bigger devices such as monitors might be more top of mind for people, because they're not disposed of regularly. Batteries are perhaps the easiest to “forget” to recycle and simply throw in the trash. If you or your family uses quite a few batteries, you should set up a small box or other container next to your trash for their disposal, so you can take them to a recycling place.

For many, it's a behavior change to recycle batteries and other hazardous materials. One of the most common excuses is that they don't know where to take recyclable parts. This lab will remove that barrier. Using the Internet, find three computer recycling places near you. Is there cost for disposing of items? Consider places that will accept working components as well as ones that take anything.

Review Questions

1. You need to purchase an inkjet printer cartridge, and you want to see what chemicals are in it. How do you obtain the MSDS for this product?
   1. You are not legally allowed to have an MSDS for this product.
   2. Visit the website of the printer cartridge manufacturer.
   3. The store is required to give you one at the time of purchase.
   4. It's contained in the packaging of the printer cartridge.
2. When cleaning a monitor, you should not use cleaning solutions that contain what?
   1. Water
   2. Alcohol
   3. Ammonia
   4. All of the above
3. When considering ergonomics, where should the keyboard and mouse be placed?
   1. Level with the user's elbows
   2. Six inches below the user's elbows
   3. Six inches above the user's elbows
   4. On the computer desk where they work
4. What is the approximate minimum level of static charge for humans to feel a shock?
   1. 30 volts
   2. 300 volts
   3. 3,000 volts
   4. 30,000 volts
5. Geri, a user, is complaining of neck pain and thinks it's because of work. What should you check to see if it's a problem?
   1. If her monitor is too high or too low
   2. If her monitor is too far away or too close
   3. If her keyboard and mouse are level with her wrists
   4. If she is not sitting properly with her feet flat on the floor
6. Why does static electricity not kill you, given that it is a high-voltage shock?
   1. Short duration
   2. Low amps
   3. It's DC volts, not AC
   4. Low resistance
7. Which of the following can cause data loss via crosstalk between adjacent cables?
   1. ESD
   2. RFD
   3. EMI
   4. MSDS
8. Which of the following contains a carcinogen and therefore needs to be recycled?
   1. Laser printer toner
   2. Inkjet ink cartridges
   3. Scanners
   4. Batteries
9. In an ergonomic assessment, which of the following is true about the optimal sitting position?
   1. Feet should be flat on the floor or on a footrest.
   2. The hips should be at a 90 degree angle to the top of the legs.
   3. Elbows should be at the sides and at a 90 degree angle.
   4. A and B
   5. A and C
   6. B and C
   7. A, B, and C
10. You are recycling non-working computer parts. Which components contain capacitors and should not be opened? (Choose two.)
    1. CRT monitors
    2. LCD monitors
    3. Power supplies
    4. Spinning hard drives
11. You are configuring an office with new computers. What should you recommend the temperature be set at for optimal desktop computer performance?
    1. Warmer than is comfortable for humans
    2. The same as is comfortable for humans
    3. Colder than is comfortable for humans, but not freezing
    4. Below freezing
12. Which of the following is a more common name for ESD?
    1. Static electricity
    2. Radio frequency interference
    3. Magnetic interference
    4. Battery backup
13. You need to purchase a battery backup system for a desktop PC. What type of device do you need?
    1. API
    2. RFI
    3. UPS
    4. EMI
    5. ESD
14. You have four AA alkaline batteries that you just removed from a remote-control device. What is the recommended way to dispose of these batteries?
    1. Throw them in the trash.
    2. Flush them down the toilet.
    3. Incinerate them.
    4. Take them to a recycling center.
15. What is the optimal humidity level for computer operation?
    1. 30 percent
    2. 50 percent
    3. 70 percent
    4. 90 percent
16. What is the recommended way to get debris out from under the keys of a keyboard?
    1. Dig it out with a screwdriver.
    2. Blow it out with compressed air.
    3. Heat it until the debris burns up.
    4. Use a magnet.
17. Which of the following measures can be implemented to reduce the risk of ESD? (Choose two.)
    1. Antistatic wrist strap
    2. Antistatic bag
    3. Antistatic hair net
    4. Shuffling your feet
18. You are placing computers at users' workstations. What consideration should you make for airflow, if any?
    1. No airflow considerations need to be made.
    2. Place the system to minimize airflow around the computer to reduce dust.
    3. Place the system to maximize airflow around the computer.
    4. Place the system on the edge of the desk to maximize airflow.
19. Your home office experiences frequent power surges. You want to purchase a device to protect your computer equipment. What should you buy? (Choose two.)
    1. UPS
    2. Surge protector
    3. Power strip
    4. Power generator
20. What is the name of the directive that restricts the use of six hazardous materials in the manufacture of various types of electronic equipment?
    1. MSDS
    2. RoHS
    3. ESD
    4. EMI