Question

If the temperature of a conductor is increased, its resistance will
A) not increase.
B) increase.
C) decrease.
D) change according to the weather.

Answer 1

The absence of free electrons in a material to conduct electricity is an indication of better resistance offered by that material. A material is termed as a good conductor if it has a large number of free electrons or ions present in it. Now a change in the temperature will correspondingly change the number of free electrons present in the conductor.

Complete step by step answer.
Step 1: Try to explain the change caused by an increase in the temperature of a conductor.
A material is categorized as a conductor because of the large number of free electrons present in it. When the temperature increases, the vibration of the atoms of the conductor also increases. This causes the free electrons to collide with each other and with the other bounded electrons. These collisions reduce the energy of the free electron and they will no longer be considered as free electrons. This will then contribute to the resistance of the conductor.

So as the temperature is increased more and more, collisions between charges take place which then, in turn, cause the resistance of the material to increase as well. Given below is a graph depicting the variation of resistance of a conductor with the increase in its temperature.

Hence, if the temperature of a conductor increases, its resistance will also increase.

So the correct option is B.

Note: When sketching the graph depicting the variation of resistance of a conductor with the rise in its temperature, it is important to remember that a conductor will always offer a feeble amount of resistance even at zero units of temperature and so the variation curve cannot start at the origin. It is the free movement of electrons and ions in a material which attributes to its good conduction of electricity.