Q. When a Daniel cell is connected in the secondary circuit of a potentiometer, the balancing length is found to be 540 cm. If the balancing length becomes 500 cm when the cell is short circuited with $1\ \Omega,$ the internal of the cell is
A) $0.08\ \Omega$
B) $0.04\ \Omega$
C) $1.0\ \Omega$
D) $1.08\ \Omega$
Explanation
(a) Internal resistance,
$r = R\left( \frac{l_{1} - l_{2}}{l_{2}} \right) = 1\left( \frac{540 - 500}{500} \right) = \frac{40}{500} = 0.08\ \Omega$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.