Question

A battery of $6V$ and internal resistance $2\Omega$ is connected to a silver voltmeter. If the current of $1.5A$ flows through the circuit, the resistance of the voltmeter is

• A. $4\Omega$
• B. $2\Omega$
• C. $6\Omega$
• D. $1\Omega$
• E. $5\Omega$

Answer 1

The correct option is B $2\Omega$

Given,
$E=-6V,r=2\Omega$ and $i=1.5A$
We know that, current across a circuit,
$i=\frac{E}{r+R}$
$\Rightarrow 15=\frac{6}{2+R}$
$\Rightarrow 2+R=\frac{6}{15}$
or $R=4-2=2\Omega$.