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JEE Main 2025 (23 Jan, Shift 2) · Kirchhoff's Laws & Measuring Instruments

Kirchhoff's Laws & Measuring Instruments question from JEE Main 2025 (23 Jan, Shift 2)

Q24JEE Main 2025 · 23 JAN · SHIFT 2Easy

Kirchhoff's Laws & Measuring Instruments

A galvanometer having a coil of resistance 30 Ω30\ \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 30X Ω\frac{30}{X}\ \Omega, where XX is

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Answer: (c)

  1. S=IgGI−IgS = \frac{I_g G}{I - I_g}
  2. S=0.02×303−0.02=0.62.98=30149 ΩS = \frac{0.02 \times 30}{3 - 0.02} = \frac{0.6}{2.98} = \frac{30}{149}\ \Omega
  3. So X=149X = 149, answer (c).
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