Current Electricity

JEE Main level, single correct, medium

319 of 380

Question 319 of 380

A galvanometer having a coil of resistance 30Ω30 \Omega need 20 mA of current for full-scale deflection. If a maximum current of 3 A is to be measured using this galvanometer, the resistance of the shunt to be added to the galvanometer should be 30XΩ\frac{30}{X} \Omega, where XX is
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Answer: (B) 149

(I−Ig)R=IgG(3−0.02)×R=0.02×G⇒R=30149⇒149= Required X\begin{aligned} & \left(I-I_g\right) R=I_g G \\ & (3-0.02) \times R=0.02 \times G \Rightarrow R=\frac{30}{149} \\ & \Rightarrow 149=\text { Required } X\end{aligned}

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