Question

what is the current sensitivity of a moving galvanometer and how it can be increased? Please answer it is urgent

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Answer 1

$\red{\textbf{ANSWER}}$:-

$\blue{\textbf{Sensitivity}}$:-

It is defined as the deflection produced in the galvanometer coil $\underline{\bold{as \: per\: unit\: current}}$passed through it,

i.e. $\blue{\texttt{sensitivity}}$= ø/i

$\blue{\texttt{From the theroy of galvanometer, }}$

ø/i= $\frac{BAN}{c}$

The best method to increase the sensitivity of galvanometer is to increase the value of $\underline{\bold{magnetic\: feild}}$ intensity B, which is done by using a radial magnetic field.

$\blue{\texttt{The sensitivity of galvanometer}}$ can also be increased by increasing the $\underline{\bold{area}}$ (A) of the coil or by increasing number turn (N) in the coil or by decreasing the value of $\underline{\bold{restoring\: torque}}$r(C) of the suspension fibre.

•But these values can be changed only in the limited wats as any large change in the $\underline{\bold{values}}$ of these factors creates a number of other problems.

Answer 2

An easy way is to optically magnify the notion with a mirror attached to the moving coil and a laser beam directed at it from a stationary position. The moving spot on the wall in the next room would be incredibly sensitive.

A more ambitious improvement would use a magnetic bearing to suspend the coil and perhaps a solar cell connected to it, in a vacuum. Then the laser beam used to magnify deflection could also be the source of the current to be measured.

The ultimate device would have all of the above with a beam splitter and create an interference pattern on the far surface to supplement spot movement with vernier detail.