How to Calculate a Current Through a Resistor
- 1
Use the color code to find the resistance.widerstand, resistor image by Sascha Zlatkov from Fotolia.com
Read the resistance, according to the value or color code (see Resources) printed on the resistor. You may also measure the resistance with the ohmmeter function of your multimeter if the resistor can be disconnected from the circuit. Write down the resistance value. As an example, assume the value of the resistor, R1, is 250 ohms. - 2
Find the voltage with your multimeter.multim?¡§tre et cables image by Tadzio from Fotolia.com
Measure and record the voltage drop across the resistor, using the voltmeter function of your multimeter.
Assume a voltage drop of 50 volts across the resistor R1, as an example. - 3). Divide the measured voltage drop across the resistor by the resistance in ohms of the resistor to find the current through the resistor. In this example, find the current through R1 by dividing 50V by 250 ohms: 0.2 amps.
