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How to Measure Resistance of Carbon Resistors

Resistors function by reducing electrical current and voltage; they release energy as heat. Resistors may fail when they are disconnected, physically broken, overloaded or burnt up. Resistors are typically designed as power loads and are made of a variety of materials for different purposes including radio frequency, signal work and direct current. Resistors range in application from light bulbs, oil cooled resistors, to surface mount resistors. Testing carbon resistors, or any resistor is critical to detecting failure.

Things You'll Need

Carbon resistor
Volt Ohmmeter

Instructions

- 1
  Place the resistor on a flat working surface. Clean the contact points of any corrosion or damage for a good physical and electrical connection. Read the color codes and compare to a color code chart to determine your ohmmeter setting.
- 2
  Switch your volt-ohmmeter to the resistance setting based on the color codes on the resistor. Place both leads on opposite ends of the resistor.
- 3
  Take a reading from the volt-ohmmeter. An infinite reading indicates failure or incorrect volt-ohmmeter range setting. Reset and test again to verify the reading.

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