Q. In a potentiometer experiment the balancing with a cell is at length 240 cm. on shunting the cell with a resistance of 2$\ \Omega$, the balancing length becomes 120cm. the internal resistance of cell is
A) 4$\ \Omega$
B) 2$\ \Omega$
C) 1$\ \Omega$
D) 0.5$\ \Omega$
Explanation
(b) Here, $r = \frac{l_{1} - l_{2}}{l_{2}} \times 2\Omega$
Where $l_{1} = 240\ cm,\ l_{2} = 120\ cm$
$\therefore\ \ \ r = \frac{240 - 120}{120} \times 2$
$\ \ \ \ \ \ \ \ \ \ \ = \frac{120}{120} \times 2 \times 2\Omega$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.