# In a potentiometer experiment it is found that no current flows through the galvanometer when balancing length is 52 cm of potentiometer when shant resistance of $5 \Omega$ is used balancing length becomes 40 cm The internal resistance of cell is

$(a)\;1.5 \Omega \\(b)\;3\; \Omega \\(c)\;\large\frac{52}{5} \; \Omega \\(d)\; 2 \;\Omega$

Internal resistance $r=\bigg(\large\frac{L-l}{l}\bigg)$
$\qquad= \bigg(\large\frac{32-40}{40} \bigg)$
$\qquad= 1.5 \Omega$
Hence a is the correct answer.