HARD
8th Tamil Nadu Board
IMPORTANT
Earn 100

Explain three ways of charge transfer.

Important Points to Remember in Chapter -1 - Electricity from Tamil Nadu Board Standard Eight Science Solutions

1. Charge and its Basic Properties:

(i) Electric charge: Basic property of matter carried by some elementary particles.

(ii) Electric charge can be positive or negative.

(iii) Opposite charges attract each other and like charges repel each other.

2. Methods of Charging:

(i) The transfer of charges from one region to another region can take place by any of the following ways:

(a) Transfer by friction.

(b) Transfer by conduction.

(c) Transfer by induction.

(ii) Electric conductor: A material through which electric current passes easily.

(iii) Insulator: A material which does not allow the electricity to pass through it.

(iv) Friction between objects results in transfer of electrons between them. 

(v) When a charged body touches another body, charges can be transferred from one body to another.

(vi) Induction is a process of charging an uncharged body by bringing a charged body near to it but not touching it.

3. Electroscope:

Electroscope: A scientific instrument used to detect the presence of electric charge on a body.

4. Lightning and Thunder:

(i) Lightning is produced by discharge of electricity from cloud to cloud or from cloud to ground.

(ii) Earthing: A safety measure devised to prevent people from getting shocked if the insulation inside electrical devices fails.

(iii) Lightning arrester or lightning conductor is a device used to protect buildings from the effects of lightning.

5. Effects of Current:

(i) Electric current: The flow of electrons.

(ii) Potential difference: Electrons flow from lower potential to higher potential. The difference between these potentials is known as potential difference or voltage.

(iii) Electric cell: A device which converts the energy of chemicals into electric energy.

(iv) Secondary cell: A cell that can be recharged many times.

(v) Battery: A combination of two or more electric cells.

(vi) Electric circuit: The continuous path from the positive terminal of an electric cell to its negative terminal through which the electric current flows.

(vii) Open circuit: In a circuit if the key is in open (off) condition, then electricity will not flow and the circuit is called an open circuit. 

(viii) Closed circuit: In a circuit if the key is in closed (on) condition, then electricity will flow and the circuit is called a closed circuit. 

(ix) Types of circuits:

(a) Simple circuit: A circuit consisting of a cell, key, bulb and connecting wires.

(b) Series circuit: If two or more bulbs are connected in series in a circuit.

(c) Parallel circuit: If two or more bulbs are connected in parallel in a circuit.

(x) Electrolysis: The decomposition of molecules of a solution into positive and negative ions on passing an electric current through it.

(xi) Fuse: A strip of alloy wire which is made of lead and tin with a very low melting point.