## 30-second summary

## Induction Type Voltmeter

Induction type voltmeter works on the principle of mutual induction. It can only be used for the measurement of ac power, whereas the electrodynamometer type can be used for both ac and dc.

The induction wattmeter is useful with circuits having constant supply and frequency. AC supply produces flux, which induces eddy current, and the interaction of eddy current and flux causes deflecting torque. Due to their simple construction, these voltmeters are the most often used voltmeters. On the other hand, it has lower accuracy because of the heavy-moving system.

Other types of voltmeters are:

**Voltmeter – Symbol of Voltmeter**

In circuit diagrams, a voltmeter is represented by the letter V in a circle, with two emerging lines representing the two points of measurement.

## Voltmeter and Hydraulic Analogy

The hydraulic analogy, or the electric-fluid analogy, is a widely used analogy between hydraulics and electricity, which is a useful tool for teaching and for those who are struggling to understand how circuits work. it can also be applied to heat transfer problems.

Since electric current is invisible and the processes in play in electronics are often difficult to demonstrate, the various electronic components are represented by hydraulic equivalents. The relationship between voltage and current is defined (in ohmic devices like resistors) by Ohm’s law. Ohm’s Law is analogous to the Hagen–Poiseuille equation, as both are linear models relating flux and potential in their respective systems.

Electricity (as well as heat) was originally understood to be a kind of fluid, and the names of certain electric quantities (such as current) are derived from hydraulic equivalents.

**Voltage** is like the pressure difference that pushes water through the hose. It is measured in volts (V). This model assumes that the water is flowing horizontally so that the force of gravity can be ignored. So that voltmeter is equivalent to pressure difference measurement.