To know the resistance G of a galvanometer by half deflection method, a battery of emf VE and resistance R is used to deflect the galvanometer by angle θ. If a shunt of resistance S is needed to get half deflection then G, R and S are related by the equation: (a) 2S (R + G) = RG (b) S (R + G) = RG (c) 2S = G (d) 2G = S

Answer: (b). Without shunt: Ig = E/R+G. With shunt: total current (E)/(R + GS/G+S), galvanometer share Ig' = (ES)/(R(G+S) + GS). Half deflection: (ES)/(R(G+S)+GS) = (E)/(2(R+G)) ⇒ 2S(R+G) = RG + RS + GS ⇒ S(R+G) = RG. So the answer is (b).

To know the resistance G of a galvanometer by half deflection method… | JEE Main 2016 (9 Apr, Shift 1)

Q22JEE Main 2016 · 9 APR · SHIFT 1Medium

Moving Coil Galvanometer, Ammeter & Voltmeter

To know the resistance G of a galvanometer by half deflection method, a battery of emf VE and resistance R is used to deflect the galvanometer by angle $\theta$ . If a shunt of resistance S is needed to get half deflection then G, R and S are related by the equation:

Show answer and solution

Answer: (b)

Without shunt: $I_g = \frac{E}{R+G}$ .
With shunt: total current $\frac{E}{R + \frac{GS}{G+S}}$ , galvanometer share $I_g' = \frac{ES}{R(G+S) + GS}$ .
Half deflection: $\frac{ES}{R(G+S)+GS} = \frac{E}{2(R+G)} \Rightarrow 2S(R+G) = RG + RS + GS$
$\Rightarrow S(R+G) = RG$ . So the answer is (b).

Report a mistake

Moving Coil Galvanometer, Ammeter & Voltmeter question from JEE Main 2016 (9 Apr, Shift 1)

More questions on Moving Coil Galvanometer, Ammeter & Voltmeter