Question

In an experiment for calibration of voltmeter, a standard cell of emf 1.5V is balanced at 375cm length of potentiometer wire. The potential difference across a resistance in the circuit is balanced at 1.25 m. If a voltmeter is connected across the same resistance, it reads 0.6V. The error in the voltmeter is

• A. 0.1V
• B. 0.025V
• C. 0.235V
• D. 0.18V

Answer 1

The correct option is A 0.1V

$i\rho =\frac{E}{l}=\frac{1.5}{3.75}\frac{V}{m}{V}^1=\left(i\rho \right)l=\frac{1.5}{3.75}\times 1.25V^1=0.5VError=V-V^1=0.6-0.5=0.1V$