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# Selina solutions for Class 9 Physics chapter 10 - Magnetism

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## Chapter 10: Magnetism

Exercise - 10(A)Exercise - 10(B)

#### Selina solutions for Class 9 Physics Chapter 10 Exercise Exercise - 10(A) [Pages 207 - 208]

Exercise - 10(A) | Q 1 | Page 207

What is a lodestone?

Exercise - 10(A) | Q 2 | Page 207

What is a natural magnet? State two limitations of a natural magnet.

Exercise - 10(A) | Q 3 | Page 207

What is an artificial magnet? State two reasons why do we need artificial magnets .

Exercise - 10(A) | Q 4 | Page 207

How will you test whether a given rod is made of iron or copper?

[Hint : Iron rod gets magnetised when placed near a bar magnet by magnetic induction, while copper rod does not get magnetised]

Exercise - 10(A) | Q 5 | Page 207

You are provided with two similar bars, one is a magnet and the other is a soft iron. How will you distinguish between them without the use of any other magnet or bar?

[Hint : A magnet when suspended freely will rest only in the north-south direction, but the soft iron bar will rest in any direction]

Exercise - 10(A) | Q 6.1 | Page 207

Fill in the blank to complete the sentence :

The two ends of a magnet are called __________.

Exercise - 10(A) | Q 6.2 | Page 207

Fill in the blank to complete the sentence :

Unlike poles of a magnet ___________ each other.

Exercise - 10(A) | Q 6.3 | Page 207

Fill in the blank to complete the sentence :

Like poles of a magnet ______________ each other.

Exercise - 10(A) | Q 6.4 | Page 207

Fill in the blank to complete the sentence :

A freely suspended magnet rests in the geographic ___________ direction.

Exercise - 10(A) | Q 7 | Page 207

A small magnet is suspended by a silk thread from a rigid support such that the magnet can freely swing. How will it rest? Draw a diagram to show it.

Exercise - 10(A) | Q 8 | Page 207

Explain the meaning of the term induced magnetism.

Exercise - 10(A) | Q 9 | Page 207

Explain what you understand by magnetic induction. What role does it play in attraction of a piece of iron by a magnet?

Exercise - 10(A) | Q 10 | Page 207

Explain the mechanism of attraction of iron nails by a magnet when brought near them.

Exercise - 10(A) | Q 11.1 | Page 207

Explain the following :

When two pins are hung by their heads from the same pole of a magnet, their pointed ends moves apart.

Exercise - 10(A) | Q 11.2 | Page 207

Explain the following :

Several soft iron pins can cling, one below the other, from the pole of a magnet.

Exercise - 10(A) | Q 11.3 | Page 207

Explain the following :

The north end of a freely suspended magnetic needle gets attracted towards a piece of soft iron placed a little distance away from the needle.

Exercise - 10(A) | Q 12 | Page 207

A small iron bar is kept near the north pole of a bar magnet. How does the iron bar acquire magnetism? Draw a diagram to show the polarity on the iron bar. What will happen if the magnet is removed?

Exercise - 10(A) | Q 13 | Page 207

'Induced magnetism is temporary'. Comment on this statement.

Exercise - 10(A) | Q 14 | Page 207

'Induction precedes attraction'. Explain the statement.

Exercise - 10(A) | Q 15 | Page 207

What do you understand by the term magnetic field lines?

Exercise - 10(A) | Q 16 | Page 207

State four properties of magnetic field lines.

Exercise - 10(A) | Q 17 | Page 207

Explain why iron filings which are sprinkled on a sheet of cardboard placed over a bar magnet take up a definite pattern when cardboard is slightly tapped.

Exercise - 10(A) | Q 18 | Page 207

Explain the method of plotting the magnetic field lines by using a small compass needle.

Exercise - 10(A) | Q 19 | Page 207

Can two magnetic field lines intersect each other? Give reason to your answer.

Exercise - 10(A) | Q 20.1 | Page 207

In following figure, draw at least two magnetic field lines between the two magnets.

(a)

Exercise - 10(A) | Q 20.2 | Page 207

In following figure, draw at least two magnetic field lines between the two magnets.

(b)

Exercise - 10(A) | Q 21 | Page 208

State two evidences of the existence of earth's magnetic field.

Exercise - 10(A) | Q 22 | Page 208

Sketch four magnetic field lines as obtained in a limited space on a horizontal plane in the earth's magnetic field alone.

Exercise - 10(A) | Q 23.1 | Page 208

Draw the pattern of magnetic field lines near a bar magnet placed with its North Pole pointing towards the geographic North. Indicate the position of neutral points by marking X.

Exercise - 10(A) | Q 23.2 | Page 208

State whether the magnetic field lines in part (a) represent a uniform magnetic field or non-uniform magnetic field?

Exercise - 10(A) | Q 24.1 | Page 208

Figure. shows a bar magnet placed on the table top with its north pole pointing towards south. The arrow shows the north-south direction. There are no other magnets or magnetic materials nearby.

Insert two magnetic field lines on either side of the magnet using  arrow head to show the direction of each field line.

Exercise - 10(A) | Q 24.2 | Page 208

Figure. shows a bar magnet placed on the table top with its north pole pointing towards south. The arrow shows the north-south direction. There are no other magnets or magnetic materials nearby.

Indicate by crosses, the likely positions of the neutral points.

Exercise - 10(A) | Q 24.3 | Page 208

Figure. shows a bar magnet placed on the table top with its north pole pointing towards south. The arrow shows the north-south direction. There are no other magnets or magnetic materials nearby.

What is the magnitude of the magnetic field at each neutral point? Give a reason for your answer.

Exercise - 10(A) | Q 25 | Page 208

What conclusion is drawn regarding the magnetic field at a point if a compass needle at that point rests in any direction? Give reason for your answer.

Exercise - 10(A) | Q 26 | Page 208

What is a neutral point? How is the position of neutral point located with the use of a compass needle?

Exercise - 10(A) | Q 27 | Page 208

State the positions of neutral points when a magnet is placed with its axis in the magnetic meridian and with its north pole (i) pointing towards the geographic north and (ii) pointing towards the geographic south.

Exercise - 10(A) | Q 28.1 | Page 208

Complete the following sentence :

If the field lines in a magnetic field are parallel and equidistant, the magnetic field is __________  .

Exercise - 10(A) | Q 28.2 | Page 208

Complete the following sentence :

At a neutral point, the resultant magnetic field is ___________.

Exercise - 10(A) | Q 28.3 | Page 208

Complete the following sentence :

The neutral points of a bar magnet kept with its north pole pointing towards geographic north are located ____________.

#### Selina solutions for Class 9 Physics Chapter 10 Exercise Exercise - 10(A) [Page 208]

Exercise - 10(A) | Q 1 | Page 208

Two like magnetic poles:

• Repel each other

• Attract each other

• First attract each other, then repel

• Neither attract nor repel.

Exercise - 10(A) | Q 2 | Page 208

In a uniform magnetic field, the field lines are:

• Curved

• Parallel equidistant straight lines

• Parallel but non-equispaced straight lines

• Nothing can be said.

#### Selina solutions for Class 9 Physics Chapter 10 Exercise Exercise - 10(B) [Pages 211 - 212]

Exercise - 10(B) | Q 1 | Page 211

What is an electromagnet?

Exercise - 10(B) | Q 2 | Page 211

Name the material used for preparing an electromagnet.

Exercise - 10(B) | Q 3 | Page 211

How is an electromagnet made? Name two factors on which the strength of magnetic field of the electromagnet depends.

Exercise - 10(B) | Q 4 | Page 211

You are required to make an electromagnet from a soft iron bar by using a cell, an insulated coil of copper wire and a switch.

1. Draw a circuit diagram to represent the process.
2. Label the poles of the electromagnet.
Exercise - 10(B) | Q 5 | Page 211

Following Figure shows a coil wound around a soft iron bar XY. (a) State the polarity at the ends X and Y as the switch is pressed. (b) Suggest one way of increasing the strength of electromagnet so formed.

Exercise - 10(B) | Q 6 | Page 211

A coil of insulated copper wire is wound around a piece of soft iron and current is passed in the coil from a battery. What name is given to the device so obtained? Give one use of the device mentioned by you.

Exercise - 10(B) | Q 7 | Page 212

Show with the aid of a diagram how a wire is wound on a U-shaped piece of soft iron in order to make it an electromagnet. Complete the circuit diagram and label the poles of the electromagnet.

Exercise - 10(B) | Q 8 | Page 212

State two ways through which the strength of an electromagnet can be increased.

Exercise - 10(B) | Q 9 | Page 212

Name one device that uses an electromagnet.

Exercise - 10(B) | Q 10 | Page 212

State two advantages of an electromagnet over a permanent magnet.

Exercise - 10(B) | Q 11 | Page 212

State two differences between an electromagnet and a permanent magnet.

Exercise - 10(B) | Q 12 | Page 212

Why is soft iron used as the core of the electromagnet in an electric bell?

Exercise - 10(B) | Q 13 | Page 212

How is the working of an electric bell affected, if alternating current be used instead of direct current?

Exercise - 10(B) | Q 14 | Page 212

Name the material used for making the armature of an electric bell. Give a reason for your answer.

#### Selina solutions for Class 9 Physics Chapter 10 Exercise Exercise - 10(B) [Page 212]

Exercise - 10(B) | Q 1 | Page 212

Electromagnets are made up of :

• steel

• copper

• soft iron

• aluminium

Exercise - 10(B) | Q 2 | Page 212

The strength of the electromagnet can be increased by

• reversing the directions of current

• using alternating current of high frequency

• increasing the current in the coil

• decreasing the number of turns of coil

## Chapter 10: Magnetism

Exercise - 10(A)Exercise - 10(B)

## Selina solutions for Class 9 Physics chapter 10 - Magnetism

Selina solutions for Class 9 Physics chapter 10 (Magnetism) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CISCE Selina ICSE Concise Physics for Class 9 solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 9 Physics chapter 10 Magnetism are Induced Magnetism, Magnetic Field of Earth, Neutral Points in Magnetic Fields, Lines of Magnetic Field and Their Properties, Introduction of Electromagnet and Its Uses.

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