Question

A voltmeter reading upto 100 mV is calibrated by a potentiometer. An emf of 1.08 V is balanced across 5.4 m length of the wire. When voltmeter reading is 0.9 V, the balancing length is 4.55 m. The error in the voltmeter reading is

• A. $0.01V$
• B. $0.1V$
• C. $0.001V$
• D. $0V$

Answer 1

Answer: (A)

$0.01V$

$K=\frac{V}{L}=\frac{1.08}{5.4}$

$V^{{}^{\prime }}=Kl=\frac{1.08}{5.4}\times 4.55=0.91V$

$Error=0.9-0.91=-0.01$