Electricity and Magnetism ICSE Class-7th Concise Selina Physics Solutions

Electricity and Magnetism ICSE Class-7th Concise Selina Physics Solutions Chapter-7. We Provide Step by Step Answer of Objective, True False , Fill in the blanks,Match the following , Short/Long Answer Type of Exercise-7 Electricity and Magnetism. Visit official Website  CISCE  for detail information about ICSE Board Class-7.

Electricity and Magnetism ICSE Class-7th Concise Selina Chapter-7


A. Objective Questions Chapter-7 Electricity and Magnetism ICSE Concise Selina

1. Write true or false for each statement

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(a) A current carrying coil when suspended freely can rest in any direction.
Answer. False.

(b) A coil carrying current behaves like a magnet.
Answer. True.

(c) In an electromagnet, the core is made up of copper.
Answer. False.

(d) An electric bell uses an electromagnet.
Answer. True.

(e) An electromagnet with soft iron core is a temporary magnet.
Answer. True.

(f) We use cell as the source of electricity to run an electric immersion rod.
Answer. False.

(g) A torch bulb glows if the terminals of the bulb are connected to the terminals of a cell by the metallic wire.
Answer. True.

(h) Wool is a conductor of electricity.
Answer. False.
Wool is a insulator of electricity.

(i) Silver is an insulator of electricity.
Answer. False.
Silver is good conductor of electricity.

(j) Our body is a conductor of electricity.
Answer. True.

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(k) For a circuit to be complete, every part of it must be made up of conductors.
Answer. True.

(l) All metals are conductors of electricity.
Answer. True.

(m) The switch should not be touched with wet hands.
Answer. True.

(n) A switch is an on-off device in an electric circuit.
Answer. True.


2. Fill in the blanks Solutions of Electricity and Magnetism ICSE Class-7th

(a) A magnet has two poles.
(b) Like poles repel each other and unlike poles attract.
(c) An electromagnet is used to separate large mass of iron scrap.
(d) The strength of magnetic field of an electromagnet is increased by inserting a core of soft iron.
(e) In a torch we use dry cell as the source of electricity.
(f) To light a table lamp and to run a refrigerator, we use mains as the source of electricity.
(g) A group of two or more cells is called a battery.
(h) Conductors pass electricity through them.
(i) Insulators do not pass electricity through them.


3. Match the following Electricity and Magnetism ICSE Class-7th

Match the following


4. Select the correct alternative Electricity and Magnetism ICSE Class-7th

(a) A freely suspended magnet rests in

  1.  east-west direction
  2.  north-south direction
  3.  north-east direction
  4.  north-west direction.

Answer

 north-south direction

(b) Electromagnets are made up of

  1.  steel
  2.  copper
  3.  brass
  4.  soft iron.

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Answer

soft iron.

(c) An electromagnet is used in

  1. electric oven
  2.  ammeter
  3.  electric bell
  4.  radio set.

Answer

electric bell

(d) The purpose of armature in an electric bell is

  1.  to make and break the circuit
  2.  produce sound
  3.  produce magnetic field
  4.  to provide spring action.

Answer

to make and break the circuit

(e) In a torch, the source of electricity is

  1.  the bulb
  2.  the switch
  3.  the cell
  4.  the mains.

Answer

the cell

(f) Electricity can flow through

  1. wood
  2.  rubber
  3.  plastic
  4. copper wire.

Answer

copper wire.

(g) Electricity does not flow through

  1.  human body
  2.  animals body
  3.  rubber
  4.  silver.

Answer

rubber

(h) We should not touch the switch with wet hands otherwise

  1.  electricity may pass through our body
  2.  electricity may not pass through the appliance
  3.  circuit may break
  4.  the switch may get off.

Answer

electricity may pass through our body


B. Short/Long Answer Questions Electricity and Magnetism ICSE Class-7th

Question 1.

State two properties of a bar magnet.
Answer:
Properties of a bar magnet

  1.  Attractive property: A magnet attracts small pieces of iron, cobalt or nickel.
  2.  Directive property: A magnet when suspended freely, always point towards North and South direction.
  3.  Like poles, i.e. North and North or South and South poles repel each other.
  4.  Unlike poles i.e. North and South attract each other.
  5.  Poles always exist in pairs, i.e. poles of a magnet cannot be separated.

Question 2.

How will you test whether a given rod is a magnet or not?
Answer:
Aim— To test whether a given rod is a magnet or not.
Apparatus —

  1. od to be tested
  2.  a bar magnet
  3.  a stand
  4.  a thread

Procedure 

  1.  Suspend the rod to be tested with a thread on the stand.
  2.  Bring the bar magnet near the rod with its north pole towards the rod’s end.
  3.  Observe.

Inference — In every case, the magnet comes to rest in a north- south direction which shows its directive property.
Observation and Inference —

— If the rod is attracted towards the bar magnet, the rod may be magnet or not.
— But if the rod remains in the same direction of rest as in the start of the experiment, it show it is not a magnet.

Question 3.

How will you test whether a given rod is made of iron or not?
Answer:
Bring a magnet near the rod if the rod is attracted by the magnet then it will be made of iron else not.

Question 4.

You are given two similar bars. One is a magnet and the other is of soft iron. How will you distinguish and identify them ?
Answer:
Take first bar and suspend it in a stand with the help of a thread. So that it is free to rotate in horizontal plane. Note the direction in which it sets itself. If the direction is North and South it may be magnet. Again rotate it, if this time again it sets itself in north and south direction, it is a magnet, otherwise, it is iron.
Now repeat above experiment with second bar and in the same way find it if it sets always in north and south direction then it will be a magnet.

Question 5.

You are given a magnet. How will you use it to find north-south direction at a place?
Answer:

The earth is a huge magnet in itself with its North and South poles. The North and South of the place can easily be detected with the help of a bar magnet. A freely suspended bar magnet always rest in the geographic N-S direction. Since the South pole of the earth’s magnet is closer to the geographic North, the North pole of the suspended magnet will always rest in the geographic North, and the South pole of the freely suspended magnet will point towards geographic South.

Question 6.

Describe a simple experiment to illustrate that like poles of two magnets repel each other while the unlike poles attract.
Answer:
Like poles repel and unlike poles attract.
Two like poles (both North poles or both South poles) repel each other. Two unlike poles (one North pole and the other South pole) attract each other. This can be demonstrated by the following simple experiment.

Take two bar magnets A and B. Suspend one magnet A with a silk thread from a support so that it is free to swing. The magnet A will come to rest in the North-South direction. The North pole of the magnet A is in the North direction and its South pole is in the South direction. Now holding the other magnet B in your hand if you bring its North pole near the North pole of the suspended magnet A as shown in figure you will observe that the two poles repel each other. Care is taken that the two magnets do not touch each other.

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