## Revision Notes of Ch 14 Electric Current and its Effects Class 7th Science

Topics in the chapter

• What is electric current?
• Electronic component
• Electric circuit
• Heating effect of electric current
• Magnetic effect of electric current
• Electromagnet
• Electric bell

What is electric current?

→ It is a flow of electrons through a conductor.

→ It flows through a wire, the wires gets heated. It is the heating effect of current.

Electronic component

→ It can be an element of an electric circuit that helps in its functioning.

• Electric circuit: It allows electricity to flow through it and is used to provide electricity for various purposes such as running electric motors providing electricity to a bulb or a fan, generating heat.

• Battery: Battery is a combination of two or more cells. The positive terminal of one cell is connected to the negative terminal of another cell.

Electric circuit

→ It helps the symbols that are used for representing the electronic components.

Types of circuit

→ There are two types of circuit:

(i) Open circuit: When the key is opened or switched off the circuit is said to be an open circuit.

(ii) Close circuit: When the key is closed or switched on the circuit is said to be a closed circuit.

Heating effect of electric current

→ Wire gets heated up when an electric current passes through it.

• The heat produced in the wire depends upon the following factors:
(i) Length of wire
(ii) Material of wire
(iii) Thickness of wire

• Examples of appliances works on the heating effect of electric current:
(i) Iron
(ii) Electric heater
(iii) Electric stove
(iv Geysers

• Fuse: It prevent damage to electric circuit. It is act as a safety device.

• MCB: MCB stands for miniature circuit breakers. MCB is a switch which automatically turn off when current in a circuit exceeds the safe limit.

Magnetic effect of electric current

→ Passing of electric current through a wire it behaves like magnet. This is called magnetic effect of the electric current.

→ It is discovered by a scientist Hans Christian Oersted.

Electromagnet

→ It is a coil of wire wound on a soft iron core which is used to separate magnetic material from the junk.

→ It is formed because the magnetic effect of the electric current.

• Application of electromagnets:

→ Used in toys
→ Used in electric bells
→ Used in all kinds of telecommunication equipment

Electric bell

→ In electric bell there is electromagnet is present in it.

→ It has a coil of wire wound around a piece of iron.

→ The iron strip with a hammer is kept close to the electromagnet and also there is a contact screw near the iron strip.

→ When iron strip is in contact with the screw the current flows through the coil and acts as electromagnet.

→ Then it pulled the strip and hammer at the end of the strip strikes the gong of the bell and produces sound.

NCERT Solutions of Electric Current and its Effects Class 7