Solids exhibit an amazing range of electrical conductivities, extending over 27 orders of magnitude ranging from 10^–20 to 10⁷ ohm^–1 m^–1.

Solids can be classified into three types on the basis of their conductivities.

(i) Conductors: The solids with conductivities ranging between 10⁴ to 10⁷ ohm^–1m^–1 are called conductors. Metals have conductivities in the order of 10⁷ ohm^–1m^–1 are good conductors.

(ii) Insulators: These are the solids with very low conductivities ranging between 10^–20 to 10^–10 ohm^–1m^–1.

(iii) Semiconductors: These are the solids with conductivities in the intermediate range from 10^–6 to 10⁴ ohm^–1m^–1.

Which of the following combination represents diode?

One n-type combined with other p- type semiconductor

The correct answer is option 3. One n-type combined with other p- type semiconductor

Applications of n-type and p-type semiconductors

Various combinations of n-type and p-type semiconductors are used for making electronic components.

Diode is a combination of n-type and p-type semiconductors and is used as a rectifier.

Transistors are made by sandwiching a layer of one type of semiconductor between two layers of the other type of semiconductor. npn and pnp type of transistors are used to detect or amplify radio or audio signals.

The solar cell is an efficient photo-diode used for conversion of light energy into electrical energy.