Question

If the voltmeter reads $0.2V$ and the ammeter reads $0.101A$, the resistance of the voltmeter is (in $\Omega$)

• A. 500
• B. 1000
• C. 200
• D. 4001

Answer 1

Answer: (C)

200

Assume current in 2 $\Omega$ is $L^{{}^{\prime }}$ and current in Voltmeter is

$L_0^{{}^{\prime }}$ and resistance of voltmeter is $x$

Reading of voltmeter $=0.2V$

$\Rightarrow 0.2V=L^{{}^{\prime }}\times 2$

$L^{{}^{\prime }}=0.1$

$\Rightarrow L_0^{{}^{\prime }}=0.101-0.1$

$=0.001$

The current is being divided in ratio of $2:x$ between voltmeter and 2

$\Omega$

$\Rightarrow L_0^{{}^{\prime }}=0.101\times \frac{2}{2+x}$

$\frac{1}{101}=\frac{2}{2+x}$

$2+x=202$

$x=200\Omega$