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प्रश्न
State two differences between an electromagnet and a permanent magnet.
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उत्तर
| Electromagnet | Permanent magnet |
| It is made up of soft iron | It is made up of steel. |
| The magnetic field strength can be changed. | The magnetic field strength cannot be changed. |
| The electromagnets of very strong field can be made. | The permanent magnets are not so strong. |
संबंधित प्रश्न
The diagram shows a coil wound around a U shape soft iron bar AB.
1) What is the polarity induced at the ends A and B when the switch is pressed?
2) Suggest one way to strengthen the magnetic field in the electromagnet
3) What will be the polarities at A & B if the direction of current is reversed in the circuit?
Name and state the rule by which polarity at the ends of a current carrying solenoid is determined.
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.
State two factors on which the magnitude of an induced e.m.f. in the secondary coils of a transformer depends.
What is an electromagnet?
How does a magnetic field set up by a solenoid change when a soft iron core is inserted inside solenoid?
Why is soft iron generally used as the core of the electromagnet?
State two advantages of an electromagnet over a bar magnet.
What is dynomo (a.c. generator)? State the principle on which it works.
The primary windings of a step-up transformer are usually made of thicker wire than the secondary. Explain.
