Question

A voltmeter has an internal resistance of 1000$\Omega$ and gives full scale deflection when 2 V is applied across the terminals. Now a resistance of 4000 $\Omega$ is connected in series with it. Then it gives full scale deflection with

• A. 8 V
• B. 10 V
• C. 6 V
• D. 4 V

Answer 1

The correct option is B 10 V

$\frac{V_1}{V_2}=\frac{R_1}{R_2}=\frac{2}{V_2}=\frac{1000}{1000+4000}$
Since $Req=R_1+R_2$
$V_2=10V$