Physics

Problem

In a moving coil galvanometer, torque on the coil can be expressed as

\tau = ki

, where

i

is current through the wire and

k

is constant. The rectangular coil of the galvanometer having number of turns

N

, area

A

and moment of inertia

I

is placed in magnetic field

B

. Find a.

k

in terms of given parameters

N, I, A

and

B

b. the torsion constant of the spring, if a current

i_0

produces a deflection of

\pi/2

in the coil. c. the maximum angle through which the coil is deflected, if charge

Q

is passed through the coil almost instantaneously. (ignore the damping in mechanical oscillations).