NCERT Revision Notes for Chapter 14 Electric Current and its Effects Class 7 Science
CBSE NCERT Revision Notes1
Answer
- What is electric current?
- Electronic component
- Electric circuit
- Heating effect of electric current
- Magnetic effect of electric current
- Electromagnet
- Electric bell
2
Answer
→ 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.
3
Answer
→ 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.
4
Answer
→ 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.
5
Answer
→ 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.
6
Answer
→ 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.