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A moving coil galvanometer of resistance 100 Ω 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

Asked in JEE Main 24th Jan 2nd Shift 2026 · Conversion to ammeter and voltmeter

• (1) 2.5
• (2) 0.5
• (3) 10
• (4) 25

Step-by-step solution

Why the other options are wrong

• (1) Power-of-ten slip: divided G by 40 instead of by n - 1 = 4 (with n = I/(I_g) = 5).
• (2) Divided G by 200 (mixed mA and A) instead of by n - 1 = 4.
• (3) Divided G by 10 instead of by n - 1 = 4.

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