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Postby TGTS0907129» Sensitivity of galvanometer

Describe the sensitivity of galvanometer


The deflection caused by a given current depends upon the design of the instrument; this characteristic is known as the sensitivity of the galvanometer. There are numerous ways of expressing galvanometer sensitivity, each involving a statement of the electrical conditions necessary to produce a stranded deflection. This standard deflection is galvanometers having attracted scales id assumed to be one scale division. In galvanometers not equipped with scales (for example, galvanometers read with auxiliary telescope and scale) the standard deflection is assumed to be 1 mm on a scale at a distance of 1 m. some of the most frequently used methods of expressing galvanometer sensitivity follow.
As previously stated, the galvanometer deflection s is proportional to the current I,
s ∝ I, or I = ks
k = I/s

where, k, the current per standard unit deflection is called the current sensitivity of the galvanometer.
For sensitive galvanometers which are read with telescope and scale, the current sensitivity k is expressed in microamperes per millimeter deflection on a scale 1 m from the mirror. The current in microamperes (millionths of an ampere, commonly abbreviated μA) required to cause a 1-mm deflection of the image on a scale 1 m distant. For the highly sensitive types of d’ Arsonval galvanometers, k is about 0.00001 μA/mm, or 10-11 A/mm. other expressions of galvanometer sensitivity are derived from the current sensitivity. It should be carefully noted that the term sensitivity is a technical words meaning the reciprocal of sensitiveness. A sensitive galvanometer has a low sensitivity k.

By TGTT06081269 on 2/4/2016 11:17:38 PM
TGTS0907129 on 1/28/2016 10:23:13 PM

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