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A string galvanometer is a sensitive fast-responding measuring instrument that uses a single fine filament of wire suspended in a strong magnetic field to measure small currents. In use, a strong light source is used to illuminate the fine filament, and the optical system magnifies the movement of the filament allowing it to be observed or ...
In a device called an oscillograph, the moving beam of light is used, to produce graphs of current versus time, by recording measurements on photographic film. The string galvanometer is a type of mirror galvanometer so sensitive that it was used to make the first electrocardiogram of the electrical activity of the human heart.
In electrical engineering, current sensing is any one of several techniques used to measure electric current. The measurement of current ranges from picoamps to tens of thousands of amperes. The selection of a current sensing method depends on requirements such as magnitude, accuracy, bandwidth, robustness, cost, isolation or size. The current ...
Measures current Capacitance meter: Measures the capacitance component Current clamp: Measures current without physical connection Curve tracer: Applies swept signals to a device and allows display of the response Cos Phi Meter: Measures the power factor Distortionmeter: Measures the distortion added to a circuit Electricity meter
To measure larger currents, a resistor called a shunt is placed in parallel with the meter. The resistances of shunts is in the integer to fractional milliohm range. Nearly all of the current flows through the shunt, and only a small fraction flows through the meter. This allows the meter to measure large currents.
In electrical and electronic engineering, a current clamp, also known as current probe, is an electrical device with jaws which open to allow clamping around an electrical conductor. This allows measurement of the current in a conductor without the need to make physical contact with it, or to disconnect it for insertion through the probe.
A measuring instrument is a device to measure a physical quantity. In the physical sciences , quality assurance , and engineering , measurement is the activity of obtaining and comparing physical quantities of real-world objects and events .
Combined with an internal voltage source, the current measuring mode can be adapted to measure very high resistances, of the order of 10 17 Ω. Finally, by calculation from the known capacitance of the electrometer's input terminal, the instrument can measure very small electric charges, down to a small fraction of a picocoulomb.
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