Q. The potential difference in open circuit for a cell is $2.2\ volt.$ When a $4\ ohm$ resistor is connected between its two electrodes the potential difference becomes $2\ volt.$ The internal resistance of the cell will be
A) $1\ ohm$
B) $0.2\ ohm$
C) $2.5\ ohm$
D) $0.4\ ohm$
Explanation
(d) $E = 2.2\ V,\ R = 4\ \Omega,\ V = 2V$
$r = \left( \frac{E}{V} - 1 \right)R = \left( \frac{2.2}{2} - 1 \right) \times 4 = 0.1 \times 4 = 0.4\Omega$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.