A cell supplies a current of 0.9 A through a 2 Ω resistor and a current of 0.3 A through a 7 Ω resistor. The internal resistance of the cell is

Question

A cell supplies a current of 0.9 A through a 2 Ω resistor and a current of 0.3 A through a 7 Ω resistor. The internal resistance of the cell is (A) 2.0 Ω (B) 1.2 Ω (C) 1.0 Ω (D) 0.5 Ω

Tardigrade Admin · Accepted Answer

E = I1 (R1 + r) and E = I2 (R2 + r) i.e. E = 0.9 (2 + r) and E = 0.3 (7 + r) i.e. 1.8 + 0.9 r = 2.1 + 0.3r i.e. x = (0.3/0.6) = 0.5 Ω

Q. A cell supplies a current of 0.9 A through a $2 Ω$ resistor and a current of 0.3 A through a $7 Ω$ resistor. The internal resistance of the cell is

$2.0 Ω$

$1.2 Ω$

$1.0 Ω$

$0.5 Ω$

E = $I_{1} (R_{1} + r)$ and E = $I_{2} (R_{2} + r)$ $i . e .$ E = 0.9 (2 + r) and E = 0.3 (7 + r) $i . e .$ 1.8 + 0.9 r = 2.1 + 0.3 $r$ $i . e .$ $x = \frac{0.3}{0.6} = 0.5 Ω$

Q. A cell supplies a current of 0.9 A through a 2Ω resistor and a current of 0.3 A through a 7Ω resistor. The internal resistance of the cell is

2.0Ω

1.2Ω

1.0Ω

0.5Ω