Magnetism Exe-10B Long Ans Concise Physics ICSE Class 9 Selina Publishers Solutions. Very important long Questions with answer on Electromagnet and its Uses topics. Visit official Website CISCE for detail information about ICSE Board Class-9 Physics.
Magnetism Exe-10B Long Ans Concise Physics ICSE Class 9 Selina Publishers Solutions
| Board | ICSE |
| Class | 9 |
| Subject | Physics |
| Writer / Publication | Concise selina Publishers |
| Chapter-10 | Magnetism |
| Exe-10B | Electro magnet and its Uses |
| Topics | Solution of Exe-10B Long Answer Type |
| Academic Session | 2025-2026 |
Electro Magnet and its Uses
Magnetism Exe-10B Long Ans Concise Physics ICSE Class 9 Selina Publishers Solutions.
Page 236
LONG ANSWER TYPE:
Que-1: How is an electromagnet made? Name two factors on which the strength of the magnetic field of an electromagnet depends.
Ans: An electromagnet is made by winding an insulated copper wire around a soft iron core either in the shape of a solenoid or U-shape and passing current through it.
The strength of magnetic field of an electromagnet depends on: 1=>The number of turns of wire wound around the coil, and 2=>The amount of current flowing through the wire.
Que-2: 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.
Ans: An electromagnet is a coil of current-carrying wire wound around an iron core as shown in the attached figure. When connected to a current source, the electromagnet becomes energised, creating a magnetic field just like a permanent magnet. The polarity of an electromagnet can be determined using right-hand thumb rule.
Que-3: State two differences between an electromagnet and a permanent magnet.
Ans:
| Difference Between Electromagnet and Permanent Magnet | |
|---|---|
| Electromagnet | Permanent Magnet |
| The magnetic properties are displayed when current is passed through it | Magnetic properties exist when the material is magnetised |
| The strength is adjusted depending upon the amount of flow of current | The strength depends upon the nature of the material used in its creation |
| Removal of magnetic properties is temporary | Once magnetic properties are lost, it becomes useless |
| It requires a continuous supply of electricity to maintain its magnetic field. | It doesn’t require a continuous supply of electricity to maintain its magnetic field |
| It is usually made of soft materials | It is usually made of hard materials |
| The poles of this kind of magnet can be altered with the flow of current | The poles of this kind of magnet cannot be changed. |
Que-4: 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 electro magnet.
Ans: An electromagnet is simply a coil of wire. It is usually wound around an iron core. However, it could be wound around an air core, in which case it is called a solenoid. When connected to a current source, the electromagnet becomes energized, creating a magnetic field just like a permanent magnet.
How polarity of the electromagnet is determine
The polarity of the electromagnet is determined by the direction the current. The north pole of the electromagnet is determined by using our right hand. If we wrap our fingers around the coil in the same direction as the current is flowing (conventional current flows from + to -). The direction our thumb is pointing is the direction of the magnetic field, so north would come out of the electromagnet in the direction of our thumb.
Above is the circuit diagram of an electromagnet on a horse shoe shaped core with the poles marked and direction of current indicated.
Que-5: Describe the construction and working of an electric bell with the help of a neat and labelled diagram.
Ans: Construction of an electric bell:
Following are the components of an electric bell:
1. Electromagnet: A copper wire is wound around an iron piece which acts a magnet when current flows through it.
2. Striker in touch with contact screw through an iron strip.
3. A metal gong.
4. A key or a switch.
Working of an electric bell: When the switch is ‘ON’ and the screw is in contact with the iron strip, then electric current flows through the copper wire which gets magnetised because of electromagnetism. This magnetised copper wire (or the electromagnet) attracts the iron strip towards it, letting the striker hit the gong and thus sound is produced. As soon as the striker hits the gong, the screw loses its contact with the iron strip and therefore, current stops in the circuit. At this point, the electromagnet loses its magnetism and the iron strip moves back and comes in contact with the contact screw. The electric current is then restored in the circuit and again the striker hits the gong by the above process. This action repeats itself and the bell rings.
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