Question

The actual value of resistance $R$, shown in the figure is $30 \Omega$. This is measured in an experiment as shown using the standard formula $R = \frac{V}{I}$ , where $V$ and $I$ are the readings of the voltmeter and ammeter, respectively. If the measured value of $R$ is $5\%$ less, then the internal resistance of the voltmeter is :

• A. 350 $\Omega$
• B. 570 $\Omega$
• C. 35 $\Omega$
• D. 600 $\Omega$

Answer 1

Answer: (B)

570 $\Omega$

Answer 2

$0.95 R = \frac{RR_{v}}{R+R_{v}}$
$0.95 \times30 = 0.05 R_{v}$
$R_{v} = 19 \times30 = 570\, \Omega$