Voltmeter

A voltmeter is an instrument that measures the electric potential difference, or voltage, between two points in a circuit, and it is connected in parallel with the section of circuit being measured, using a high internal resistance so it draws as little current as possible. An analog voltmeter typically works by moving a pointer across a scale in proportion to the voltage measured, and can be built from a galvanometer wired in series with a resistor, while more sensitive amplified versions can detect voltages as small as microvolts and digital voltmeters use an analog to digital converter to show the reading as a number. Voltmeters can be powered by their own battery or draw power from the circuit they measure, and besides reading voltage directly they are also used, once calibrated, to measure related quantities such as pressure or temperature. The first digital voltmeter was built by Andrew Kay in 1954. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/