# What is a voltmeter?

The device that makes it possible to measure the difference in potential or voltage existing between two points belonging to an electrical circuit is called a voltmeter. The voltmeter therefore reveals the voltage (the number of volts).

The voltmeters must have a high electrical resistance so that, when connected to the circuit to perform the measurement, they do not generate a consumption that leads to an erroneous measurement of voltage. According to its operation, it is possible to differentiate between more than one type of voltmeter. The digital voltmeter has a screen where it reflects the voltage with numbers. These devices may also have memory and other functions.

The vector voltmeter, in turn, uses microwave signals to indicate the voltage and its phase. The electromechanical voltmeter finally has a galvanometer with graduated scale volts. It is important not to confuse the voltmeter with the voltmeter. While the voltmeter measures voltage (electrical potential), the voltmeter is responsible for measuring the electrical charge. Voltmeters reflect their results in volts and voltmeters do so in coulombs. There should also be no confusion between the voltmeter and the ammeter, which is the tool used to measure the intensity of current. The voltmeter, to work, has to be connected in parallel: the ammeter, on the other hand, in series, so that the current passes through it. Its resistance, therefore, must be low, not high as in the case of the voltmeter. When we talk about putting the voltmeter in parallel, we are referring to the concept of an electrical circuit in parallel, and this is defined as a connection in which the input ports of each device (such as capacitors, resistors and generators) connect and coincide between each other. itself, as well as its output terminals. If we think about two water tanks for a second, connecting them in parallel would make them share the same inlet, which would feed both simultaneously, and the same outlet, which would drain both at the same time. In order for the voltmeter to be placed in parallel, it must have an internal resistance as high as possible, so that the consumption it produces is not considerable, otherwise errors may occur in the voltage measurement. In instruments that are based on the electromagnetic effects produced by the electric current, the voltmeters must have thin wire coils with a large number of turns, thanks to which it is possible to reach the necessary moment for the pointer to move with a small value of current intensity. It is worth noting that the term momentum, in this case, is defined as “a physical magnitude that, while the system changes, remains constant”.

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There are digital versions of the voltmeter that are used today and have a very high isolation capacity thanks to the use of specific circuits of high complexity. When we want to measure voltages that exceed the limits of a voltmeter (in the case of digital, the limit of its electronic circuits; in the case of others, of its mechanical organs and windings), we must resort to a resistance of high value and place it in series. with it, so that only a part of the total tension reaches them. Anyone interested in the repair or maintenance of their electronic devices should have a voltmeter, as it is an essential tool for making preliminary measurements, as well as verifying that the work has gone as expected.