Arrange the following in the increasing order of their resistance.
(A) Resistance of an ideal ammeter.
(B) Resistance of a shunt.
(C) Resistance of a voltmeter.
(D) Resistance of galvanometer.
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → (A), (B), (D), (C)
An ammeter is placed in series, so it must have very low resistance; a voltmeter is placed in parallel, so it must have very high resistance. Both are made from a galvanometer.
\( R_{\mathrm{ideal\ ammeter}} = 0 \)
\( R_{\mathrm{shunt}} \ll R_{G} \ll R_{\mathrm{voltmeter}} \)
(A) Resistance of an ideal ammeter: zero resistance, so it does not change the current it measures.
(B) Resistance of a shunt: a very small resistance joined in parallel with the galvanometer, so that most of the current bypasses the galvanometer.
(D) Resistance of galvanometer: a moderate resistance (typically tens of ohms), much more than the shunt.
(C) Resistance of a voltmeter: the galvanometer in series with a large resistance, so its total resistance is the highest of the four.
Increasing order: (A), (B), (D), (C).
NCERT (2026-27):
The Moving Coil Galvanometer – “… (ii) For measuring currents, the galvanometer has to be connected in series, and as it has a large resistance, this will change the value of the current in the circuit. To overcome these difficulties, one attaches a small resistance rs, called shunt resistance, in parallel with the galvanometer coil; so that most of the current passes through the shunt.”
The Moving Coil Galvanometer – “… (c) is an ideal ammeter with zero resistance?”
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.”