Three moving coil galvanometer A,B and C are made of coils of three different material having torsional constrant `1.8xx10^(-8), 2.8xx10^(-8)` and `3.8xx10^(-8)` respectively if the three galvanometer are identical in all other respect then in which of the above cases sensitivity maximum

Options

A. A
B. C
C. B
D. same in each case

Answer

A

Explanation

If `theta` is the deflection in the galvanometer when current l is passed through it thenn
current sensitivity `l_(s)=(theta)/(l)=(nBA)/(k)`
where k be restoring torque per unit twist n be number of turns in the coil B is strenght of magnetic field in which coil is suspended A be area of coil sinc restoring torque per unit twist (trosional constant ) is minimum for galvanometer A hence it will be more sensitvie