Name: Tips for Electrical Safety
Uploaded: 2019-07-19
Duration: 1 min 24 s
Description: Electricity, one of the most useful discoveries, results in some dangerous accidents when used carelessly. To avoid such accidents, we need to take safety pr...

Question

Sohail hung an object A on a spring as shown in the figure given below. He placed an electromagnet below A and recorded the length of the spring. He repeated the experiment with objects

B

and

C

.

The table below shows the length of the spring when the switch was ON.

Object	Length of spring when the switch was ON $(cm)$	Length of spring when the switch was OFF $(cm)$
$A$	$15$	$12$
$B$	$15$	$15$
$C$	$15$	$19$

(a) Which of the three objects is definitely a magnet?

(b) How did you conclude the above result?

(c) What can you say about the property of the material used to make object $C$ ? Justify your answer.

Accepted Answer

Coils of wire with electricity running through them make up electromagnets. An electromagnet's wire coils act like magnets when an electric current flows through them because moving charges produce magnetic fields. When an object is placed near the electromagnet, it will get attracted to the magnet if it is a magnetic material. And, if the object is a non magnetic material, then it will not be affected by the electromagnet.

(a) Object $C$ is definitly a magnet.

(b) This is because when object $C$ is placed near the electromagnet with its switch ON, the length of the spring increased. This happened because object $C$ got attracted to the electromagnet.

(c) We can magnetise only magnetic materials. Iron bar can be magnetised by induction. Steel and alnico are alloys that consist mainly of iron are used to make permanent magnets. So iron is the most suitable material for making a magnet. Iron is an easily available magnetic material.

Important Questions on Electricity and Magnetism

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