Question

You are given an ammeter, a galvanometer and a voltmeter. From these, the device having maximum resistance is

• A. ammeter
• B. galvanometer
• C. voltmeter
• D. all will have the same resistance

Answer 1

The Correct Option is C

Electric circuit diagram of ammeter, galvanometer and voltmeter is shown below, $(i)$ Ammeter

$\Rightarrow R_{eq \left(A\right) } = \frac{R_{s}R_{G}}{R_{G} +R_{s} }$ $(ii)$ Galvanometer

$\Rightarrow R_{eq \left(G\right) } =R_{G} $ $(iii)$ Voltmeter

$\Rightarrow R_{eq \left(v\right) } =R_{G} +R_{V} $ Hence, the order of resistances $ R_{eq \left(v\right) } > R_{req\left(G\right)} > R_{eq\left(A\right)} $ So, the maximum resistance device is voltmeter.