# How Does an Analog Voltmeter Work?

Whether digital or analog, a voltmeter is subject to an electrical theory known as Ohm’s Law. Ohm’s Law describes the interrelationships in an electrical circuit. The mathematical formula depicting Ohm’s Law is given in a variety of ways. One is P=IE. In this equation P, or Power, is equal to I (current) times E (voltage). This can be further simplified using resistance, voltage and current. In this case current would be the result of voltage divided by resistance. Or, resistance is the result of voltage divided by current. Analog and digital meters can be used to measure these values in a circuit. Below you will find a brief description of how an analog meter measures voltage.

The Display

An analog voltmeter gives readings by deflecting a pointer along an analog scale. On most analog meters, there is a rotating switch which chooses between resistance scales across the meter face. There will normally be a 20 Volt scale, a 200 Volt scale, a 2000 Volt scale and on some meters, a 20,000 Volt scale. These scales will correspond to the setting of the rotary switch. These settings will be separate for alternating and direct current.