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How to Make an Ohmmeter

Resistance is a quantity often determined in electrical circuits and is a direct measure of the scattering of electrons within the circuit wires. The unit of resistance is the Ohm, and Ohm's law states there is a linear relationship between voltage and current within metals. A simple resistance (Ohm) meter can be made from a voltmeter, an ammeter and a number of banana cables. The resistance is then simply calculated from the readings measured on the voltmeter and ammeter.

Things You'll Need

Ammeter
Voltmeter
Banana cables

Instructions

- 1
  Connect the ammeter to the circuit using the available banana cables. The ammeter needs to go in series with the electrical component whose resistance is being measured (for example a resistor). Placing components in series means they share a common terminal so they are connected to each other directly.
- 2
  Connect the voltmeter in parallel with the electrical component whose resistance is being measured. Connection in parallel means the two components share both electrical terminals.
- 3
  Write down the reading from the voltmeter in volts. Write down the reading from the ammeter in amps. Ohm's law states: R = V / I, where "V" is the voltage in volts and "I" is the current in amps. Calculate the resistance ("R") in Ohms.

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