OHMMETERS

The instrument, which is used to measure the value of resistance between any two points in an electric circuit is called ohmmeter. It can also be used to find the value of an unknown resistor. The units of resistance are ohm and the measuring instrument is meter. So, the word “ohmmeter” is obtained by combining the words “ohm” and “meter”.

Types of Ohmmeters

Following are the two types of ohmmeters.

• Series Ohmmeter
• Shunt Ohmmeter

Now, let us discuss about these two types of ohmmeters one by one.

Series Ohmmeter

If the resistor’s value is unknown and has to be measured by placing it in series with the ohmmeter, then that ohmmeter is called series ohmmeter. The circuit diagram of series ohmmeter is shown in below figure.

The part of the circuit, which is left side of the terminals A & B is series ohmmeter. So, we can measure the value of unknown resistance by placing it to the right side of terminals A & B. 

Shunt Ohmmeter

If the resistor’s value is unknown and to be measured by placing it in parallel (shunt) with the ohmmeter, then that ohmmeter is called shunt ohmmeter. The circuit diagram of shunt ohmmeter is shown in below figure.

The part of the circuit, which is left side of the terminals A & B is shunt ohmmeter. So, we can measure the value of unknown resistance by placing it to the right side of terminals A & B.