Q. By a cell a current of $0.9\ A$ flows through $2\ ohm$ resistor and $0.3\ A$ through $7\ ohm$ resistor. The internal resistance of the cell is
A) $0.5\ \Omega$
B) $1.0\ \Omega$
C) $1.2\ \Omega$
D) $2.0\ \Omega$
Explanation
(a) $0.9(2 + r) = 0.3(7 + r) \Rightarrow 6 + 3r = 7 + r \Rightarrow r = 0.5\ \Omega$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.