7th Class Science Electric Current and Its Effects Fuses

Fuses

Category : 7th Class

*         Fuses

 

Fuse is a safety device used to protect electric circuit and other electrical devices like, bulbs, tube lights, fans, TV, refrigerators etc. from being damaged of excessive current flow.

Sometimes, due to touching of live wire with neutral wire, known as short circuit, excessive amount of current passes through the wire. This excessive amount of current causes production of large amount of heat. As a result the wire gets burnt and the house may catch fire. Overloading is another major danger which sometimes causes fire and other damages. Thus to protect our houses and other electrical appliances from these problems, fuses are used.

               

A fuse consists of a strip of low melting alloy. In case of over loading or short circuiting, the alloy wire of the fuse gets melted immediately. As a result, the circuit of electricity breaks and supplying is stopped. In this way other electrical appliances are saved from damage.

 

 

 

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question mark      The wire of greater resistance produces greater amount of heat energy' is the above statement true ?

(a) Yes                                                                 

(b) No

(c) Resistance has nothing to do with heat

(d) All of these

(e) None of these

 

Answers (a)

 

 

question mark       Which one of the following is an insulator?

(a) Water

(b) Human body

(c) Dried wood

(d) Iron nail

(e) None of these

 

Answer: (c)

 

 

summary.jpg

Flow of electrons through a wire is called electricity.

The path, in which electrons move to produce electricity, is called electric circuit.

A simple electric circuit is composed of a battery, wire and a switch.

Fuse is a safety device which protects the electric appliances in case of short circuiting and overloading.

When current is passed from a wire the heat energy is produced, the phenomenon is known as heating effect of current.

Bulb is an instrument, which works on the heating effect of current.

When current moves from a conductor wire, it acts as a bar magnet. This phenomenon is known as magnetic effect of current.

Electric bell works on magnetic effect of current.



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