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

Answer: (C)

voltmeter

Answer 2

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.