The galvanometer deflection , when key `K_(1)` is closed but `K_(2)` is open equals `theta_(0)` (see figure ) On closing `k_(2)` also and adjusting `R_(2) ` to ` 5Omega` , the deflection in galvanometer becomes `(theta_(0))/(5)` the resistnce of the galvanometer is then , given by [Neglect the internal resistance of battery]:

Options

A. `22Omega`
B. `25Omega`
C. `12Omega`
D. `5Omega`

Explanation

Deflection in galvanometer is proportional to galvanometer current
`theta_0 prop ig implies theta_0 K=ig`
Situation 1 , `K theta_0=V/(220+R)`………(i)
Situation `(K theta_0)/5=V/((220+(5R)/(5+R)) times 5/( 5+R)`
From (i) and (2) , `R=22 Omega`