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A moving coil galvanometer is converted into an ammeter by connecting:
AA small resistance in series
BA large resistance in series
CA large resistance in parallel
DA small resistance in parallel
Answer & Solution
Correct answer: D. A small resistance in parallel
1. An ammeter must carry large current yet barely disturb the circuit, so it needs very low resistance.
2. Connecting a small shunt resistance $r_s$ in parallel diverts most of the current around the coil.
3. The combined resistance becomes small (≈ $r_s$ when $R_G \gg r_s$).
4. A series large resistance would instead make a voltmeter, so that option is wrong.
_Source: NCERT Class 12 Physics Ch 4 "Moving Charges and Magnetism", p.160_
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