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JEE Main 2013 (9 Apr, Shift 1) · Kirchhoff's Laws & Measuring Instruments

Kirchhoff's Laws & Measuring Instruments question from JEE Main 2013 (9 Apr, Shift 1)

Q186JEE Main 2013 · 9 APR · SHIFT 1Easy

Kirchhoff's Laws & Measuring Instruments

A shunt of resistance 1 Ω\Omega is connected across a galvanometer of 120 Ω\Omega resistance. A current of 5.5 ampere gives full scale deflection in the galvanometer. The current that will give full scale deflection in the absence of the shunt is nearly:

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Answer: (d)

  1. With the shunt, current through galvanometer Ig=ISS+GI_g = I\frac{S}{S + G}.
  2. Ig=5.5×11+120=5.5121≈0.045 AI_g = 5.5 \times \frac{1}{1 + 120} = \frac{5.5}{121} \approx 0.045\text{ A}
  3. Without the shunt this same IgI_g gives full scale, so the answer is (d) 0.045 ampere.
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