The subject Physics being an important branch of science contains fascinating theories, instruments, and discoveries. One of such inventions is the Voltmeter also known as voltage meter which is an instrument that measures the voltage or potential difference among two points of an electronic or electrical circuit. Usually, these instruments are used for Alternating Current circuits or Direct Current circuits. The Radio Frequency (RF) voltage could be measured by specialized voltmeters.

A galvanometer (current meter) that is sensitive and is part of a high resistance series is what makes a basic analog voltmeter. The meter should have a high internal resistance. Else the circuit operation during the test would be interrupted by drawing current significantly. The voltage range displayed by the meter is determined by the series resistance value and the galvanometer sensitivity.

Voltage is shown directly in numeral form by the digital voltmeter. Voltage measurement as values up to certain significant level could be determined by some of these meters. From 1000 to 3000 volts are the maximum ranges of these practical laboratory voltmeters. Different scales those have power increases like 0-1 V, 0-100 V and so on are manufactured as commercial voltmeters.

To measure low voltages, on the other hand, oscilloscope could be used where instantaneous voltage would be depicted by the vertical displacement. RF and AC applications have their peak to peak and peak voltage measured by the oscilloscopes. Wiring, insulators and heavy duty probes are crucial for making the meters for measuring high potential differences.

Another voltmeter which is quite used among voltage measurement instruments is the digital voltmeter.A digital voltmeter (DVM) measures an unknown input voltage by converting the voltage to a digital value and then displays the voltage in numeric form. DVMs are usually designed around a special type of analog-to-digital converter called an integrating converter. There are different factors that have an impact on the accuracy of the DVM like input impedance, temperature, and power supply voltage variations of the DVM. Around 10 M? is the input resistance of DVMs that are the least expensive. The input resistances for precision DVMs of 1 G ? or higher for ranges of low voltages (below 20 V).

The DVM must be periodically calibrated with a voltage standard like the Weston Cell as a way to ensure that the manufacturer’s[a1]  specified tolerances.

From the above discussion, you would have realized as to why Voltmeters are used everywhere for different reasons and it would continue to do so in the years to come.

Practise This Question

Charge is continuously fed to a conductor. What should the minimum charge density at any point be to give corona discharge when the conductor is kept in air?
(Dielectric strength of air is 3,000,000Vm