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Physics · Current Electricity

JEE Main 2026 — 24 January, Evening Shift — Question 38

A moving coil galvanometer of resistance 100Ω100 \Omega shows a full scale deflection for a current of 1 mA . The value of resistance required to convert this galvanometer into an ammeter, showing full scale deflection for a current of 5 mA , is ____\_\_\_\_ Ω\Omega

  1. Option A:

    25

    Correct
  2. Option B:

    10

  3. Option C:

    0.5

  4. Option D:

    2.5

Answer: A

Step-by-step solution

G=100Ωig=1 mAi=5 mA\begin{aligned} & \mathrm{G}=100 \Omega & \mathrm{i}_{\mathrm{g}}=1 \mathrm{~mA} & \mathrm{i}=5 \mathrm{~mA} \end{aligned} r_s = \dfrac{G}{\left( \dfrac{i-1}{i_g} \right)} = \dfrac{100}{\left( \dfrac{5-1}{1} \right)} = 25\,\Omega \end{gathered}$$
Solution figure

Answer key and solution verified before publishing.

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Exam
JEE Main 2026
Paper
24 January, Evening Shift
Subject
Physics
Chapter
Current Electricity
Topic
Electrical Measuring Instruments

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