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प्रश्न
Point out three differences between an electromagnet and a bar (or permanent) magnet.
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उत्तर
| Electromagnet | Bar Magnet |
| 1. An electromagnet exhibits a much stronger magnetic field. | A bar magnet is not able to exhibit a strong magnetic field. |
| 2. Its polarity can be reversed by reversing the direction of current flowing in the turns of the coil (or solenoid). | Its polarity is fixed. |
| 3. It is a temporary magnet, it behaves as a magnet only when the current flows through the solenoid. | It is a permanent magnet and cannot be readily demagnetized. |
संबंधित प्रश्न
State two ways of magnetising an iron piece?
You are given an iron nail, a torch cell, and a long piece of insulated copper wire. With the help of a labelled neat diagram, describe in steps how you will make the nail, an electromagnet.
Tick the most appropriate answer.
Which of the following methods is used to magnetize a magnetic without touching it by a magnet?
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.
How does a magnetic field set up by a solenoid change when number of turns are increased?
State the condition when an electric charge can give rise to a magnetic field.
The primary windings of a step-up transformer are usually made of thicker wire than the secondary. Explain.
A current-carrying solenoid is suspended so as to freely rotate in a horizontal plane. State in what direction will it rest. Give a reason for your answer.
or
When a solenoid that is carrying current is freely suspended, it comes to rest in a particular direction. Why does this happen?
(i) A straight wire conductor passes vertically through a piece of cardboard sprinkled with iron filings. Copy the diagram and show the setting of iron filings when a current is passed through the wire in the upward direction and the cardboard is tapped gently. Draw arrows to represent the direction of the magnetic field lines.
(ii) Name the law which helped you to find the direction of the magnetic field lines.
How does a magnetic field set up by a solenoid change when cross-sectional area of solenoid is increased?
