Explanation for Method of Monitoring Current from a Power Supply
The 10 ohm resistor is simple acting as a current to voltage converter since it is in series with the load. By Ohm's law, the voltage across the resistor in volts is simply 10 times the current through the resistor in amperes. However, the conversion factor is such that the current in milliamperes will be 1/10 the voltage in millivolts since the value of the resistor is 10 0hms.