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An early D'Arsonval galvanometer showing magnet and rotating coil. A galvanometer is an electromechanical measuring instrument for electric current.Early galvanometers were uncalibrated, but improved versions, called ammeters, were calibrated and could measure the flow of current more precisely.
A moving coil galvanometer can be used as a voltmeter by inserting a resistor in series with the instrument. The galvanometer has a coil of fine wire suspended in a strong magnetic field. When an electric current is applied, the interaction of the magnetic field of the coil and of the stationary magnet creates a torque, tending to make the coil ...
The galvanometer does not need to be calibrated, as its only function is to read zero or not zero. When measuring an unknown voltage and the galvanometer reads zero, no current is drawn from the unknown voltage and so the reading is independent of the source's internal resistance, as if by a voltmeter of infinite resistance.
Ammeter and Voltmeter on a power supply. Electrical measurements are the methods, devices and calculations used to measure electrical quantities. Measurement of electrical quantities may be done to measure electrical parameters of a system.
When a voltmeter is connected between two different types of metal, it measures the potential difference corrected for the different atomic environments. [6] The quantity measured by a voltmeter is called electrochemical potential or fermi level , while the pure unadjusted electric potential, V , is sometimes called the Galvani potential , ϕ .
Resistance thermometer principle: relation between temperature and electrical resistance of metals (platinum) (electrical resistance), range: 10 to 1,000 kelvins, application in physics and industry; Solid thermometer principle: relation between temperature and length of a solid (coefficient of thermal expansion). Bimetallic strip
Voltmeter: Measures the potential difference between two points in a circuit. (Includes: DVM and VTVM) VU meter: Measures the level of AF signals in Volume units Cathode Ray Oscilloscope (CRO) Check transistor
In this case, a separate shunt, a resistor of very low but accurately known resistance, is placed in parallel with a voltmeter, so that virtually all of the current to be measured will flow through the shunt (provided that the very high internal resistance of the voltmeter takes such a low portion of the current that it can be considered ...