Question

Effect of temperature on internal resistance of a battery is
(A) directly proportional
(B) inversely proportional
(C) no effect
(D) none of these

Answer 1

Hint: Determine the cause behind the internal resistance of a battery. Now determine the effect of temperature on the movement of ions in the electrode solutions that make up the battery. Based on this you can decide the factor that will determine the increase/decrease of internal resistance of battery.

Complete Solution :
- Internal resistance refers to the opposition to the direction or flow of current offered by the cells or rather batteries themselves resulting in the generation of heat. The SI unit of internal resistance is measured in ohms.
- The internal resistance of a battery that behaves as a voltage source affects the output voltage when current flows. However, it does not affect the amount of current that is flowing in the circuit.
- EMF is produced by the movement of ions in the solution to the respective electrodes. The obstruction offered against the movement of ions is termed as internal resistance.
- When we increase the temperature, the ions gain more energy and hence the resistance offered against their movement is reduced.
- This means that the internal resistance of a battery is inversely proportional to the temperature factor.
So, the correct answer is “Option B”.

Note: It is important to know that when external and internal resistance are involved in the same circuit, we represent internal resistance with 'r' for convenience unlike the common representation of 'R'.