When a galvanometer is shunted with a `4Omega` resistance, the deflection is reduced to `1//5`. If the galvanometer is further shounted with a `2Omega` wire, the new deflection will be (assuming the main current remains the same)

Options

A. `(24)/(25)l`
B. `(25)/(24)l`
C. `(15)/(16)l`
D. `(16)/(15)`

Answer

(B)

Explanation

`X_(cm) = (m((l)/(2)) + m ((l)/(2) + (l)/(2)) + m ((l)/(2) + (l)/(4) + (l)/(2)) + m ((l)/(2) + (l)/(4) + (l)/(6) + (l)/(2)))/(m + m + m + m) = (25)/(24)l`