Question

The potential difference in open circuit for a cell is 2.2 volts. When a 4 ohm resistor is connected between its two electrodes the potential difference becomes 2 volts. The internal resistance of the cell will be

• A. 1 ohm
• B. 0.2 ohm
• C. 2.5 ohm
• D. 0.4 ohm

Answer 1

Answer: (D)

0.4 ohm

Answer 2

$( 4 + r ) i = 2.2$ ......(i) and $i = \frac { 1 } { 2 }$

Putting the value of i in (i), we get r = 0.4 ohm.