Physics
A soft iron piece is in the form of a closed ring (no free ends). A wire is wound over it to make it an electromagnet. What happens when current is passed in the wire ?
- It does not get magnetised.
- It gets temporarily magnetised.
- It becomes magnetised.
- It can be magnetised if broken into two parts.
Magnetism
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Answer
It becomes magnetised
Reason — When the current flows through the soft iron piece in the form of a closed ring, it becomes magnetised. The north and south poles will be present on opposite sides of the ring.
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Related Questions
Which of the following statements are correct ?
(i) An electromagnet produces a permanent magnetic field.
(ii) An electromagnet can produce a strong magnetic field.
(iii) The polarity of electromagnet can be reversed by reversing the direction of current in the solenoid.
- all of the above
- (i) and (ii)
- (ii) and (iii)
- (i) and (iii)
The strength of an electromagnet can be increased by:
- reversing the directions of current
- using alternating current of high frequency
- increasing the current in the coil
- decreasing the number of turns of coil
Which of the following devices does not use an electromagnet ?
- Magnetic compass
- Electric fan
- Relay
- Microphone
The magnetic polarity at the two ends of a horse-shoe magnet depends on :
- the strength of current in the coil
- the number of turns in the coil
- the material on which the coil is wound
- the direction of current at the ends of the magnet.