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प्रश्न
State two differences between an electromagnet and a permanent magnet.
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उत्तर
| Electromagnet | Permanent magnet | |
| i. | It is made up of soft iron. | It is made up of steel. |
| ii. | The magnetic field strength can be changed. | The magnetic field strength cannot be changed. |
| iii. | Electromagnets of very strong field can be made. | Permanent magnets are not so strong. |
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संबंधित प्रश्न
Why is soft iron used as the core of the electromagnet in an electric bell?
The incomplete diagram of an electric bell is given in Figure. Draw winding of coil on the core and complete the electric circuit in the diagram.
G-Gong, H-Hammer, A-Armature, C-Core, B-Battery.
Electromagnets are made up of :
The strength of the electromagnet can be increased by
Name the material used for preparing an electromagnet.
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.
- Draw a circuit diagram to represent the process.
- Label the poles of the electromagnet.
The following figure shows a coil wound around a soft iron bar XY.
- State the polarity at the ends X and Y as the switch is pressed.
- Suggest one way of increasing the strength of electromagnet so formed.
State two ways through which the strength of an electromagnet can be increased.
Name one device that uses an electromagnet.
Why is soft iron used as the core of the electromagnet in an electric bell?
How is the working of an electric bell affected, if alternating current be used instead of direct current?
Name the material used for making the armature of an electric bell. Give a reason for your answer.
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Explain in detail the application of electromagnets.
Unlike magnetic poles ______ whereas like poles ______.
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Reason (R): Wires carrying current in opposite directions repel each other.
Explain the working of the following device.
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