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A voltmeter is an instrument used for measuring electric potential difference between two points in an electric circuit. It is connected in parallel . It usually has a high resistance so that it takes negligible current from the circuit.
An electrostatic voltmeter uses the attraction force between two charged surfaces to create a deflection of a pointer directly calibrated in volts. Since the attraction force is the same regardless of the polarity of the charged surfaces (as long as the charge is opposite), the electrostatic voltmeter can measure DC voltages of either polarity.
Analog multimeter Digital multimeter. A multimeter (also known as a volt-ohm-milliammeter, volt-ohmmeter or VOM) [1] is a measuring instrument that can measure multiple electrical properties.
A modern electrometer is a highly sensitive electronic voltmeter whose input impedance is so high that the current flowing into it can be considered, for most practical purposes, to be zero. The actual value of input resistance for modern electronic electrometers is around 10 14 Ω, compared to around 10 10 Ω for nanovoltmeters. [ 9 ]
A meter can be calibrated as a DC voltmeter if the resistance of the coil is known by calculating the voltage required to generate a full-scale current. A meter can be configured to read other voltages by putting it in a voltage divider circuit. This is generally done by placing a resistor in series with the meter coil.
The Hall effect type is more sensitive and is able to measure both DC and AC, [1] in some examples up to the kilohertz (thousands of hertz) range. This type was often used with oscilloscopes , and with high-end computerized digital multimeters, however, they are becoming common place for more general use.
A potentiometer being calibrated and then measuring an unknown voltage. R 1 is the resistance of the entire resistance wire. The arrow head represents the moving wiper.. In this circuit, the ends of a uniform resistance wire R 1 are connected to a regulated DC supply V S for use as a voltage divider.
These are DC amplifiers. Some types of signals that need amplifying can be so small that an incredibly high gain is required, but very high gain DC amplifiers are much harder to build with low offset and / noise, and reasonable stability and bandwidth. It's much easier to build an AC amplifier instead. A chopper circuit is used to break up the ...