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JEE Main 202523 JanuaryEvening Shift
Exam
JEE Main
Year
2025
Date
23 January
Shift
Evening Shift
Subject
Physics
Chapter
Current Electricity

JEE Main 2025 · 23 January · Evening Shift · Physics · Current Electricity

A galvanometer having a coil of resistance 30 need 20 mA of current...

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 Options

Options

  1. A596
  2. B149
  3. C298
  4. D447

Correct answer

B. 149

Step-by-step solution

(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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