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Conductor, Insulators and Semiconductors


Some materials have free electrons at room temperature. These free electrons constitute to electric current. Such materials having free electrons are termed as conductors. Conductors are used to conduct electric current from one place to other. Copper is a good conductor of electricity, hence wires are made of copper material. Wires used to transfer electric current from one place to the other.

Conductors  allow heat and sound to pass through them.

Water bodies like human body   allow electricity to pass through. Hence human bodies get shock when touch bare wire or unsafe electric equipment’s.

Definition: Conductors are materials having free electrons and conduct electric current and heat.

Examples:  Metals like Copper, Silver, Aluminium, etc. ,human body. The only non-metal conductor is Graphite.

Application: Wires, heaters, bulbs.


Insulators are materials which do  not have free electrons at room temperature. Such materials cannot conduct electric current. Insulators are the materials used to restrict, oppose or store electric charge. The insulators block heat and sound through them. Insulators are used where protection from electricity or electric current required. Anyone working with electric equipment must use safety protection like rubber hand gloves, rubber shoes and plastic covered screw drivers.

Definition:  Insulators are the materials not having free electrons and do not conduct electric current.

Examples: Glass, Mica, Rubber, Plastic, Wood etc.

Application: Sockets, Plugs, cable covering, electric hand gloves.


Semiconductors are material having few free electrons. Conductivity lies between conductors and insulators. The conductivity of Semiconductor materials are changed by adding suitable impurities.   They can be made to act like conductors or insulators.

Definition: Semiconductors are the materials having conductivity between conductors and insulators.

Examples : Silicon, Germanium, carbon etc.

Applications : Integrated circuits (ICs), Diodes, Transistors.

Difference between Conductors, Insulators and Semiconductors


Conductors Insulators Semiconductors
They have  more number of free electrons They do not have free electrons They have few free electrons.
They conduct electric current or electricity, heat, sound through them. The do not conduct electricity, heat or sound. Conductivity lies between conductors and insulators
e.g. Copper, Aluminium e.g. Rubber, Glass e.g. Silicon, Germanium
Applications- wires, heaters, lamps. Applications – outer cover of wires, sockets, plugs. Applications -Integrated circuits (ICs), Diodes, Transistors.



1.       In conductors current flows due to free…….

a)      Ions               b) electrons        c) protons           d) atoms

2.       Electric current is due to drift of ……….

a)  Ions                 b) electrons        c) protons           d) atoms

3.    Human get electric shock because they are……..

a)  Conductor     b) Insulators       c) Semiconductors

4. Graphite is ………………

a)  Conductor     b) Insulators       c) Semiconductors


Ans.       1. b        2. b         3. c         4. a


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*in 3rd question, it is said that human body is semi conductor. Then why it is mentioned it as example of conductors.

*If valence electrons gains more energy than the forces it had, it moves out from the orbit, it is then called as free electron.
– how an electron gains energy?can you please tell me.

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