If Angel wants to send Jacob a check of 50 XRP, Angel creates a transaction JSON that specifies the amount to be transferred and Jacob's Ripple address. Later, she signs the transaction using her private key and submits it to the Ripple's network for validation by calling the CheckCreate function. Once the validators confirm the transaction submitted by Angel, the check would be created. 

She can send this digital check to Jacob using any mode of communication. Once Jacob receives the digital check, he can cash it out by submitting it to Ripple's network by calling the CheckCash  function. Now, validators work to confirm whether the check submitted by Jacob is authentic. Later, it checks whether Angel has enough balance for the check to be cashed out. If Angel has enough balance, she is debited 50 XRP and Jacob's account will be credited with the same amount. However, if she doesn't have enough balance, the transaction would be rejected and Jacob can attempt again until the check expires. 

If Angel changes her mind, she will be able to cancel the check. In that case, when Jacob tries to cash out the check it would be rejected. Jacob also has the option to reject the payment by cancelling the check. 

The following diagram demonstrates how a check is created, sent and cashed out on the Ripple network:

Here's an example of the "CheckCreate" JSON that would be used by the sender to send a check of 50 XRP:

{
  "TransactionType": "CheckCreate",
  "Account": "rUn84CUYbNjRoTQ6mSW7BVJPSVJNLb1QLo",
  "Destination": "rfkE1aSy9G8Upk4JssnwBxhEv5p4mn2KTy",
  "SendMax": "50000000",
  "Expiration": 570113521,
  "InvoiceID": "6F1DFD1D0FE8A32E40E1F2C05CF1C15545BAB56B617F9C6C2D63A6B704BEF59B",
  "DestinationTag": 1,
  "Fee": "12"
}

Here's an example of the "CheckCash" JSON that would be used by the receiver to redeem a sent check:

{
    "Account": "rfkE1aSy9G8Upk4JssnwBxhEv5p4mn2KTy",
    "TransactionType": "CheckCash",
    "Amount": "50000000",
    "CheckID": "838766BA2B995C00744175F69A1B11E32C3DBC40E64801A4056FCBD657F57334",
    "Fee": "12"
}