For an ammeter, voltmeter and galvanometer having resistances \( R_{A}, R_{V} \) and \( R_{G} \) respectively, the correct relation among these resistances.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( R_{A}\lt R_{G}\lt R_{V} \)
Both instruments are made from the same galvanometer of resistance \( R_G \): an ammeter by adding a small shunt in parallel, a voltmeter by adding a large resistance in series.
Ammeter. A shunt S in parallel with \( R_G \) gives a combination smaller than either of them.
\( \displaystyle R_A = \frac{R_G S}{R_G + S} \lt R_G \)
Voltmeter. A resistance R in series with \( R_G \) gives a total larger than \( R_G \).
\( R_V = R_G + R \gt R_G \)
So \( R_A \lt R_G \lt R_V \). This is also what the instruments need: an ammeter has a very small resistance so that it does not change the current, and a voltmeter a very large one so that it draws almost no current.
NCERT (2026-27):
Summary – “… 11. A moving coil galvanometer can be converted into a ammeter by introducing a shunt resistance rs, of small value in parallel. It can be converted into a voltmeter by introducing a resistance of a large value in series.”