Question

In a potentiometer experiment, it is found that no current passes through the galvanometer when the terminals of the cell are connected across $0.52\, m$ of the potentiometer wire. If the cell is shunted by a resistance of $5\, \Omega$, balance is obtained when the cell is connected across $0.4 \,m$ of the wire. Find the internal resistance of the cell.

• A. $0.5\, \Omega$
• B. $1\, \Omega$
• C. $1.5\, \Omega$
• D. $2\, \Omega$

Answer 1

Answer: (C)

$r=R\left[\frac{l_{1}}{l_{2}}-1\right]$
$=5\left[\frac{0.52}{0.4}-1\right]$
$=5[1.3-1]=1.5\, \Omega$