Voltage Calculations:
The other use of Ohm's law is to find unknown voltages when the current and the resistance are known.
PROBLEM:
Assume that the potentiometer as shown in figure below is set to 100 ?, and the measured current is 10.0 mA. Find out the dc voltage?
SOLUTION:
Use the formula E = IR. At first, convert the current to amperes: 10.0 mA = 0.0100 A. Then multiply: E = 0.0100 x 100 = 1.00 V. This is a low, safe voltage, a slight less than what is generated by a flashlight cell.