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# Selina solutions for Concise Physics Class 10 ICSE chapter 10 - Electro-Magnetism [Latest edition]

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## Chapter 10: Electro-Magnetism

Exercise 10 (A)Exercise 10 (B)Exercise 10 (C)
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Exercise 10 (A) [Pages 239 - 241]

### Selina solutions for Concise Physics Class 10 ICSE Chapter 10 Electro-MagnetismExercise 10 (A) [Pages 239 - 241]

Exercise 10 (A) | Q 1 | Page 239

Describe an experiment to demonstrate that there is a magnetic field around a current carrying conductor.

Exercise 10 (A) | Q 2 | Page 239

Draw a diagram showing the directions of three magnetic field lines due to a straight wire carrying current. Also show the direction of current in the wire.

Exercise 10 (A) | Q 3.1 | Page 239

How is the magnetic field due to a straight current carrying wire affected if current in wire is decreased ?

Exercise 10 (A) | Q 3.2 | Page 239

How is the magnetic field due to a straight current carrying wire affected if current in wire is reversed?

Exercise 10 (A) | Q 4 | Page 239

State a law, which determines the direction of magnetic field around a current carrying wire.

Exercise 10 (A) | Q 5 | Page 239

A straight wire lying in a horizontal plane carries a current from north to south. (a) What will be the direction of magnetic field at a point just underneath it? (b) Name the law used to arrive at the answer in part (a).

Exercise 10 (A) | Q 6 | Page 239

What will happen to a compass needle when the compass is placed below a wire and a current is made to flow through the wire? Give a reason to justify your answer.

Exercise 10 (A) | Q 7 | Page 239

Draw a labelled diagram showing the three magnetic field lines of a loop carrying current. Mark the direction of current and the direction of magnetic field by arrows in your diagram.

Exercise 10 (A) | Q 8 | Page 240

A wire, bent into a circle, carries current in an anticlockwise direction. What polarity does this face of the coil exhibit?

Exercise 10 (A) | Q 9.1 | Page 240

What is the direction of magnetic field at the centre of a coil carrying current in  clockwise ?

Exercise 10 (A) | Q 9.2 | Page 240

What is the direction of magnetic field at the centre of a coil carrying current in anticlockwise direction?

Exercise 10 (A) | Q 10 | Page 240

Draw a diagram to represent the magnetic field lines along the axis of a current carrying solenoid mark arrows to show the direction of current in the solenoid and the direction of magnetic field lines.

Exercise 10 (A) | Q 11 | Page 240

Name and state the rule by which polarity at the ends of a current carrying solenoid is determined.

Exercise 10 (A) | Q 12 | Page 240

The adjacent diagram shows a small magnet placed near a solenoid AB. Current is switched on in the solenoid by pressing the key K. (a) State the polarity at the ends A and B. (b) will the magnet be attracted or repelled? Give a reason for your answer. Exercise 10 (A) | Q 13 | Page 240

The following diagram shows a spiral coil wound on a hollow carboard tube AB. A magnetic compass is placed close to it. Current it switched on by closing the key. (a) What will be the polarity at the ends A and B? (b) How will the compass needle be affected? Give reason. Exercise 10 (A) | Q 14 | Page 240

State two ways by which the magnetic field due to a solenoid can be made stronger.

Exercise 10 (A) | Q 15 | Page 240

Why does a current carrying freely suspended solenoid rest along a particular direction?

Exercise 10 (A) | Q 16 | Page 240

What effect will there be on magnetic compass when it is brought near a current carrying solenoid?

Exercise 10 (A) | Q 17 | Page 240

How is the magnetic field due to a solenoid carrying current affected if a soft iron bar is introduced inside the solenoid?

Exercise 10 (A) | Q 18.1 | Page 240

Complete the following sentence :
when current flows in a wire, it creates ………..

Exercise 10 (A) | Q 18.2 | Page 240

Complete the following sentence :

On reserving the direction of current in a wire, the magnetic field produced by it gets _____.

Exercise 10 (A) | Q 18.3 | Page 240

Complete the following sentence :

A current carrying solenoid behaves like a ……………

Exercise 10 (A) | Q 18.4 | Page 240

Complete the following sentence :

A current carrying solenoid when freely suspended, it always rests in ………. Direction .

Exercise 10 (A) | Q 19 | Page 240

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. (a) Draw a circuit diagram to represent the process. (b) label the poles of the electromagnet.

Exercise 10 (A) | Q 20 | Page 240

The adjacent diagram shows a coil would around a soft iron bar XY. (a) State the polarity at the end X and Y as the switch is pressed. (b) Suggest one way increasing the strength of electromagnet so formed. Exercise 10 (A) | Q 21 | Page 240

(a) What name is given to a cylindrical coil of diameter less than its length? (b) If a piece of soft iron is placed inside the coil mentioned in part (a) and current is passed in the coil from a battery, what name is then given to the device so obtained? (c) Give one use of the device mentioned in part (b).

Exercise 10 (A) | Q 22 | Page 240

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 (A) | Q 23.1 | Page 240

What is an electromagnet?

Exercise 10 (A) | Q 23.2 | Page 240

Name two factors on which the strength of magnetic field of an electromagnet depends and state how does it depend on the factors stated by you.

Exercise 10 (A) | Q 24.1 | Page 241

In following Figure shows the current flowing in the coil of wire wound around the soft iron horse shoe core. State the polarities developed at the ends A and B. Exercise 10 (A) | Q 24.2 | Page 241

In following figure shows the current flowing in the coil of wire wound around the soft iron horse shoe core.

How will the polarity at the ends A and B change on reversing the direction of current. Exercise 10 (A) | Q 24.3 | Page 241

In following figure shows the current flowing in the coil of wire wound around the soft iron horse shoe core.

Suggest one way increase the strength of magnetic filed produce. Exercise 10 (A) | Q 25 | Page 241

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

Exercise 10 (A) | Q 26 | Page 241

Name one device that uses an electromagnet.

Exercise 10 (A) | Q 27 | Page 241

State two advantages of an electromagnet over a permanent magnet.

Exercise 10 (A) | Q 28 | Page 241

State two differences between an electromagnet and a permanent magnet.

Exercise 10 (A) | Q 29 | Page 241

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

Exercise 10 (A) | Q 30 | Page 241

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

Exercise 10 (A) | Q 31 | Page 241

The incomplete diagram of an electric bell is given in Fig 10.21 Complete the diagram and label its different parts. Exercise 10 (A) | Q 32 | Page 241

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

Exercise 10 (A) [Page 241]

### Selina solutions for Concise Physics Class 10 ICSE Chapter 10 Electro-MagnetismExercise 10 (A) [Page 241]

Exercise 10 (A) | Q 1 | Page 241

The present of magnetic field at a point can be detected by :

• A strong magnet

• A solenoid

• A compass needle

• A current carrying wire

Exercise 10 (A) | Q 2 | Page 241

By reversing the direction of current in a wire, the magnetic field produced by it:

• Gets reversed in direction

• Increases in strength

• Decreases in strength

• Remains unchanged in strength and direction

Exercise 10 (B) [Pages 246 - 247]

### Selina solutions for Concise Physics Class 10 ICSE Chapter 10 Electro-MagnetismExercise 10 (B) [Pages 246 - 247]

Exercise 10 (B) | Q 1 | Page 246

Name three factors on which the magnitude of force on a current carrying conductor placed in a magnetic field depends and state how does the force depend on the factors stated by you.

Exercise 10 (B) | Q 2.1 | Page 246

State condition when magnitude of force on a current carrying conductor placed in a magnetic field is Zero ?

Exercise 10 (B) | Q 2.2 | Page 246

State condition when magnitude of force on a current carrying conductor placed in a magnetic field is maximum ?

Exercise 10 (B) | Q 3 | Page 246

How will the direction of force be changed, if the current is reversed in the conductor placed in a magnetic field?

Exercise 10 (B) | Q 4 | Page 246

Name and state the law which is used to determine the direction of force on a current carrying conductor placed in a magnetic field.

Exercise 10 (B) | Q 5 | Page 246

State Fleming's left handle rule.

Exercise 10 (B) | Q 6 | Page 246

State the unit of magnetic field in terms of the force experienced by a current carrying conductor placed in a magnetic field

Exercise 10 (B) | Q 7.1 | Page 246

A flat coil ABCD is freely suspended between the pole pieces of U-Shaped permanent magnet with the plane of coil parallel to the magnetic field.
What happens when a current is passed in the coil ?

Exercise 10 (B) | Q 7.2 | Page 246

A flat coil ABCD is freely suspended between the pole pieces of a U-shaped permanent magnet with the plane of coil parallel to the magnetic field.

When will coil come to rest?

Exercise 10 (B) | Q 7.3 | Page 246

A flat coil ABCD is freely suspended between the pole pieces of a U-shaped permanent magnet with the plane of coil parallel to the magnetic field.

When will the couple acting on the coil be (i) maximum, (ii) minimum?

Exercise 10 (B) | Q 7.4 | Page 246

A flat coil ABCD is freely suspended between the pole pieces of a U-shaped permanent magnet with the plane of coil parallel to the magnetic field.

Name an instrument which makes use of the principle stated above.

Exercise 10 (B) | Q 8 | Page 246

A coil ABCD mounted on an axle is placed between the poles N and S of a permanent magnet as shown in Fig. 10.28 (a) In which direction will the coil begin to rotate when current is passed through the coil in direction ABCD by connecting a battery at the ends A and D of the coil?
(b) Why is a commutator necessary for continuous rotation of the coil?
(c) Complete the diagram with commutator, ets. For the flow of current in the coil?

Exercise 10 (B) | Q 9.1 | Page 247

What is an electric motor?

Exercise 10 (B) | Q 9.2 | Page 247

principle of an electric motor ?

Exercise 10 (B) | Q 10 | Page 247

Draw a labelled diagram of a d.c. motor.

Exercise 10 (B) | Q 11 | Page 247

What energy conversion does take place during the working of a d.c. motor?

Exercise 10 (B) | Q 12 | Page 247

State two ways by which the speed of rotation of an electric motor can be increased?

Exercise 10 (B) | Q 13 | Page 247

Name two appliances in which an electric motor is used.

Exercise 10 (B) [Page 247]

### Selina solutions for Concise Physics Class 10 ICSE Chapter 10 Electro-MagnetismExercise 10 (B) [Page 247]

Exercise 10 (B) | Q 1 | Page 247

In an electric motor the energy transformation is :

• From electrical to chemical

• From chemical to light

• From mechanical to electrical

• From electrical to mechanical

Exercise 10 (C) [Pages 258 - 260]

### Selina solutions for Concise Physics Class 10 ICSE Chapter 10 Electro-MagnetismExercise 10 (C) [Pages 258 - 260]

Exercise 10 (C) | Q 1.1 | Page 258

What is electromagnetic induction?

Exercise 10 (C) | Q 1.2 | Page 258

Describe one experiment to demonstrate the phenomenon of electromagnetic induction.

In the figure:

Exercise 10 (C) | Q 2 | Page 258

State Faraday’s law of electromagnetic induction.

Exercise 10 (C) | Q 3 | Page 258

State two factors on which the magnitude of induced e.m.f. depend.

Exercise 10 (C) | Q 4.1 | Page 258

What kind of energy change takes place when a magnet is moved towards a coil having a galvanometer at its ends?

Exercise 10 (C) | Q 4.2 | Page 258

Name the phenomenon ?

Exercise 10 (C) | Q 5 | Page 258

(a) How would you demonstrate that a momentary current can be obtained by the suitable use of a magnet, a coil of wire and a galvanometer?
(b) What is the source of energy associated with the current obtained in part(a)?

Exercise 10 (C) | Q 6.1 | Page 258

Describe briefly one way producing an induced e.m.f ?

Exercise 10 (C) | Q 6.2 | Page 258

State one factor that determines the magnitude of induced e.m.f ?

Exercise 10 (C) | Q 6.3 | Page 258

What factor determines the direction of induced e.m.f?

Exercise 10 (C) | Q 7 | Page 258

Complete the following sentence:
The current induced in a closed circuit only if there is ……………..

Exercise 10 (C) | Q 8.1 | Page 258

In which of the following case does the electromagnetic induction occur?

A current is started in a wire held near a loop of wire ?

Exercise 10 (C) | Q 8.2 | Page 258

In which of the following case does the electromagnetic induction occur?
The current is stopped in a wire held near a loop of wire .

Exercise 10 (C) | Q 8.3 | Page 258

In which of the following case does the electromagnetic induction occur?

A magnet is moved through a loop of wire .

Exercise 10 (C) | Q 8.4 | Page 258

In which of the following case does the electromagnetic induction occur?

A loop of wire is held near a magnet.

Exercise 10 (C) | Q 9 | Page 258

A conductor is moved in a varying magnetic field. Name the law which determines the direction of current induced in the conductor.

Exercise 10 (C) | Q 10 | Page 258

Name and state the law which determines the direction of induced current.

or

State Fleming’s right-hand rule.

Exercise 10 (C) | Q 11 | Page 258

What is Lenz’s law?

Exercise 10 (C) | Q 12 | Page 258

Why is it more difficult to move a magnet towards a coil which has large number of turns?

Exercise 10 (C) | Q 13 | Page 258

Explain why an induced current must flow in such a direction so as to oppose the change producing it.

Exercise 10 (C) | Q 14 | Page 258

Explain the significance of Lenz’s law to show the conservation of energy in electromagnetic induction.

Exercise 10 (C) | Q 15 | Page 258

The diagram in shows a coil of several turns of copper wire near a magnet NS. The coil is moved in the direction of arrow shown in the diagram. (i) In what direction does the induced current flow in the coil?

(ii) Name the law used to arrive at the conclusion in part (i).

(iii) How would the current in coil be altered if

(a) the coil has twice the number of turns,

(b) the coil was made to move three times fast?

Exercise 10 (C) | Q 16 | Page 259

The following diagram shows a fixed coil of several turns connected to a
center zero galvanometer G and a magnet NS which can move.
(a) Describe the observation in the galvanometer if (i) The magnet is moved
rapidly in the direction of arrow, (ii ) The magnet is kept still after it has
moved into the coil, (iii ) The magnet~ then rapidly pulled out the coil. (b) How would the observation alter if a more powerful magnet is used?

Exercise 10 (C) | Q 17 | Page 259

Name and state the principle of a simple a.c. generator what is its use?

Exercise 10 (C) | Q 18 | Page 259

What determines the frequency of a.c. produced in a generator?

Exercise 10 (C) | Q 19 | Page 259

Complete the sentence:

An a.c. generator changes the ___________ energy to ___________ energy.

Exercise 10 (C) | Q 20 | Page 259

Draw a labelled diagram of a simple a.c. generator.

Exercise 10 (C) | Q 21 | Page 259

In an a.c. generator the speed at which the coil rotates is doubled. How would this affect (a) the frequency of output voltage, (b) the maximum output voltage is doubled.

Exercise 10 (C) | Q 22 | Page 259

Suggest two ways in an a.c. generator to produce a higher e.m.f.

Exercise 10 (C) | Q 23 | Page 259

What energy conversion does take place in a generator when it is in use?

Exercise 10 (C) | Q 24 | Page 259

State two dis-similarities and one similarity between a d.c. motor and an a.c. generator.

Exercise 10 (C) | Q 25 | Page 259

State one advantage of using a.c. over d.c.

Exercise 10 (C) | Q 26 | Page 259

For what purpose are the transformers used? Can they be used with a direct current source?

Exercise 10 (C) | Q 27 | Page 259

State two factors on which the magnitude of an induced e.m.f. in the secondary coils of a transformer depends.

Exercise 10 (C) | Q 28 | Page 259

How are the e.m.f in the primary and secondary coils of a transformer related with the number of turns in these coils?

Exercise 10 (C) | Q 29 | Page 259

Draw a labelled diagram to show the various components of a step-up transformer.

Exercise 10 (C) | Q 30 | Page 259

Name the device used to transform 12 V a.c. to 200V a.c. Name the principal on which it
works.

Exercise 10 (C) | Q 31 | Page 259

Draw a labelled diagram of a step-up transformer and explain how it works. State two
characteristics of the primary coil as compared to its secondary coil.

Exercise 10 (C) | Q 32 | Page 259

Draw a labelled diagram of a device you would use to transform 200 V a.c. to 15 V a.c. Name the device and explain how it works. Give its tow uses.

Exercise 10 (C) | Q 33 | Page 259

Name the coil of which the wire is thicker in a (i) step up, (ii) step down transformer. Give reason to your answer.

Exercise 10 (C) | Q 34 | Page 259

Complete the following diagram of a transformer and name the parts labelled A and B. name the part you have drawn to complete the diagram. What is the material of this part? Is this transformer a step up or step down? Give reason. Exercise 10 (C) | Q 35 | Page 260

The following diagram shows the core of a transformer and its input and output connections. (a) state the material used for core and describe its structure.

(b) complete the diagram of the transformer and connections by labelling all parts joined by you.
(c) Name the transformer: Step-up or step down?

Exercise 10 (C) | Q 36 | Page 260

The secondary windings of a transformer in which the voltage is stepped down are usually made of thicker wire than the primary. Explain why.

Exercise 10 (C) | Q 37 | Page 260

Why is the iron core of a transformer made laminated (thin sheets) instead of being in one solid piece?

Exercise 10 (C) | Q 38.1 | Page 260

Complete the following sentence:
In a step-up transformer, the number of turns in the primary are …………than the number of turns in the secondary.

Exercise 10 (C) | Q 38.2 | Page 260

Complete the following sentence :

The transformer is used in ……………. current circuits.

Exercise 10 (C) | Q 38.3 | Page 260

Complete the following sentence :

In a transformer, the frequency of A.C. voltage ________.

Exercise 10 (C) | Q 39 | Page 260

What is the function of a transformer in an a.c. circuit? How do the input and output powers in a transformer compare?

Exercise 10 (C) | Q 40 | Page 260

Name two kind of energy loss in a transformer. How is it minimized?

Exercise 10 (C) | Q 41 | Page 260

Give two points of difference between a step-up transformer and step-down transformer.

Exercise 10 (C) | Q 42 | Page 260

Name the material of core in (a) electric bell, (b) electromagnet (c) d.c motor, (d) an a.c. generator and (e) transformer.

Exercise 10 (C) | Q 43 | Page 260

Name the transformer used in the
(i) power generating station,
(ii) power sub-station.

State the function of each transformer.

Exercise 10 (C) [Page 260]

### Selina solutions for Concise Physics Class 10 ICSE Chapter 10 Electro-MagnetismExercise 10 (C) [Page 260]

Exercise 10 (C) | Q 1 | Page 260

The direction of induced current is obtained by:

• Fleming's left hand rule

• Clock rule

• Right hand thumb rule

• Fleming's right hand rule

Exercise 10 (C) | Q 2 | Page 260

In a step up transformer:

• Ns = Np

• N< Np

• N> Np

• nothing can be said

Exercise 10 (C) [Page 260]

### Selina solutions for Concise Physics Class 10 ICSE Chapter 10 Electro-MagnetismExercise 10 (C) [Page 260]

Exercise 10 (C) | Q 1 | Page 260

The magnetic flux through a coil having 100 turns decreases from 5 milli weber to zero in 5 second. Calculate the e.m.f. induced in the coil.

Exercise 10 (C) | Q 2 | Page 260

The primary coil of a transformed has 800 urns and the secondary coil has 8 turns. It is connected to a 220 V a.c. supply. What will be the output voltage?

Exercise 10 (C) | Q 3 | Page 260

A transformer is designed to work from a 240 V a.c. mains and to give a supply of 8 V to ring
a house–bell. The primary coil has 4800 turns. How many turns will be in the secondary coil?

Exercise 10 (C) | Q 4.1 | Page 260

The input and output voltage of a transformer are 220 V and 44 V respectively. Find:  the  turns ratio.

Exercise 10 (C) | Q 4.2 | Page 260

The input and output voltages of a transformer are 220 V and 44V respectively. Find the current in input circuit if the output current is 2 A.

## Chapter 10: Electro-Magnetism

Exercise 10 (A)Exercise 10 (B)Exercise 10 (C) ## Selina solutions for Concise Physics Class 10 ICSE chapter 10 - Electro-Magnetism

Selina solutions for Concise Physics Class 10 ICSE chapter 10 (Electro-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 Concise Physics Class 10 ICSE solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Concise Physics Class 10 ICSE chapter 10 Electro-Magnetism are Transformer, Electromagnetic Induction, Electro Magnetism, Magnetic Effect of Electric Current, Alternating Current (A.C.) Generator, Force on a Current Carrying Conductor in a Magnetic Field, Electromagnetic Induction, Lenz’S Law and Conservation of Energy, Eddy Currents.

Using Selina Class 10 solutions Electro-Magnetism exercise by students are an easy way to prepare for the exams, as they involve solutions arranged chapter-wise also page wise. The questions involved in Selina Solutions are important questions that can be asked in the final exam. Maximum students of CISCE Class 10 prefer Selina Textbook Solutions to score more in exam.

Get the free view of chapter 10 Electro-Magnetism Class 10 extra questions for Concise Physics Class 10 ICSE and can use Shaalaa.com to keep it handy for your exam preparation

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