Q 12-03-031NEETJEE MainMedium
A cell gives $0.5$ A through a $4\ \Omega$ resistor and $0.9$ A through a $2\ \Omega$ resistor. Its internal resistance is
Answer: (D) $0.5\ \Omega$
$E = 0.5(4 + r) = 0.9(2 + r) \Rightarrow 2 + 0.5r = 1.8 + 0.9r \Rightarrow r = 0.5\ \Omega$ (and $E = 2.25$ V).
Solution by Sreeraj P, M.Sc Physics