Question

How does the resistance of i) a semiconductor ii) an alloy vary with temperature?

Answer 1

The substance in which the space between the valence band and conduction band is less than a conductor but greater than an insulator is called the semiconductor. That means the semiconductor has less conductivity than a conductor and more conductivity than an insulator.
alloy is a mixture of metals, having one or more different elements. The mixture creates a substance having properties that can be different from the properties of pure metals. alloy is made to increase the hardness or strength.
The variation of resistance for these two types of substances is different from each other.

Complete answer:
i)Semiconductor:
A semiconductor is a substance that has less conductivity than a conductor but more conductivity than an insulator. Germanium and Silicon are these types of substances.
With the increase of the crystals of the Germanium and Silicon, the number of free electrons increases. Therefore, the resistance decreases. The graph is like this:

ii)Alloy:
An alloy is a substance that is a mixture of pure metal with some different materials. The alloy has different characteristics from pure metal. Constantan is an alloy made up of copper and nickel.
The alloy has a large resistivity due to the irregular formation of the atoms. Therefore, the change in temperature hardly affects this type of substance.

Note: For a metal, the number of free electrons increases with the increase in temperature. And hence, the resistance also increases. The graph is like this:

After mixing one or more substances to a pure metal the resistivity is increased as well as the hardness. Therefore, the temperature change does not affect the alloys.