FRANK Solutions for Class 9 Physics Chapter 8 - Electricity and Magnetism - Magnetism

Revise Science concepts easily with Frank Solutions for ICSE Class 9 Physics Chapter 8 Electricity and Magnetism – Magnetism. Learn the definitions of terms such as magnetic axis, effective length of a magnet, and poles of a magnet. Also, find out why there is a need for artificial magnets by revisiting the concepts from this chapter.

Learn about induced magnetism with the help of reference answers provided in our Frank textbook solutions. If you need more e-learning resources for revision, visit our study portal for ICSE Class 9 Physics concept videos, mock exam question papers, solved previous years’ papers and more.

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Chapter 8 - Electricity and Magnetism - Magnestism Exercise 320

Question 1

What is a natural magnet? State three properties of a magnet.

Solution 1

Natural magnet is the deposits of the iron ore which has the attracting property of iron The properties of natural magnet are :
(i) The magnet has the directive property, when it is suspended freely , it always come in north-south direction.
(ii) A magnet attracts magnetic substances like iron, steel etc. so, it has the attractive property.
(iii) Like poles repels each other while unlike poles attract each other in magnet.

Question 2
What is an artificial magnet? Why do we need artificial magnets?
Solution 2
Artificial magnets are the magnets which are formed by bringing the natural magnet near it The artificial magnets have the high retentivity means they remains magnetized for the long period of time and that is why they are used for making strong electromagnets.
Question 3
What do you understand by poles of a magnet?
Solution 3
The magnetic forces appear to be concentrated at the near ends of the magnet. These points are called the magnetic poles.
Question 4
How will you test whether a given rod is made of iron or copper?
Solution 4
Bring the rod near the magnet, iron rod will get attract towards the magnet while copper will not.
Question 5
How will you test the polarity of a magnet?
Solution 5
Suspend a magnet freely; it will always point towards the north -south direction. The pole of the magnet which point towards the north is called north pole and the pole which point towards south is called south pole.
Question 6
Define the terms:
(i) Magnetic axis
(ii) Poles of a magnet
(iii) Effective length of a magnet
Solution 6
Magnetic axis : The imaginary line joining the poles of the magnet is called magnetic axis.
Poles of the Magnet: The points of the magnet where the attraction appears to be maximum are called poles of the magnet.
Effective Length of the magnet: The distance between the poles of magnet is the effective length of magnet.
Question 7
You are given two similar bars; one is a soft iron and the other is a magnet. How will you distinguish between them without using any other magnet or bar?
Solution 7
Suspend the iron bar and magnet freely in the space by using thread. And, move them here and there few number of times. The bar which always points in north south direction after coming to rest is a magnet and other bar is the iron bar.
Question 8
Can we isolate the poles of a magnet?
Solution 8
No, we cannot isolate the poles of the magnet.
Question 9
What do you mean by induced magnetism?
Solution 9
The magnetism acquired by the magnetic material when it is kept near the magnet is called induced magnetism.
Question 10
What do you mean by the term lines of magnetic field?
Solution 10
The lines of the magnetic field are the continuous curve such that the tangent drawn at any point gives the direction of magnetic field at that point.
Question 11
What is a lodestone?
Solution 11
The natural magnet which was used for the navigation by the mariners is called lodestone.
Question 12
What is the use of a magnetic compass?
Solution 12
Magnetic compass is used to draw the magnetic field of lines around the magnet.
Question 13
Magnetic field lines intersect each other, if yes, why?
Solution 13
No, Magnetic field of lines cannot intersect each other.
Question 14
Frank Solutions Icse Class 9 Physics Chapter - Electricity And Magnetism Magnetism
Solution 14
Frank Solutions Icse Class 9 Physics Chapter - Electricity And Magnetism Magnetism
Question 15
Describe a simple experiment to demonstrate that like poles repel each other while unlike poles attract.
Solution 15
The simple experiment to show that like poles repel while unlike poles attract each other is : Suspend a bar magnet and allow it to freely rotate. When it will come to rest, it will point towards the north south direction. Now, bring the N pole of second magnet near the North pole of the suspended magnet , we will see repulsion between the two magnets. But, if we bring south pole of second magnet near the north pole of suspended magnet then we will observe attraction. So, we can say like poles repel while unlike poles attract.
Question 16
How will you plot the magnetic field lines by using a small compass needle?
Solution 16
The directions indicated by the needle of compass will help to draw the magnetic lines of force.
Question 17
What do you mean by the term neutral point?
Solution 17
Neutral points are the points where the magnetic field of magnet has the magnitude equal to the magnitude of earth's magnetic field but in opposite direction.
Question 18
What is the significance of a neutral point?
Solution 18
Neutral points help in finding the magnitude and direction of earth's magnetic field at that particular point.
Question 19
What is the resultant magnetic field at a neutral point?
Solution 19
The resultant magnetic field at neutral point is zero.