The magnetic field of an electromagnet can be increased by …………… in the solenoid and by ……………through the solenoid.

1. increasing the number of turns, decreasing the current.
2. decreasing the number of turns, increasing the current.
3. decreasing the number of turns, decreasing the current.
4. increasing the number of turns, increasing the current.

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.

1. all of the above
2. (i) and (ii)
3. (ii) and (iii)
4. (i) and (iii)

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 ?

1. It does not get magnetised.
2. It gets temporarily magnetised.
3. It becomes magnetised.
4. It can be magnetised if broken into two parts.

Which of the following devices does not use an electromagnet ?

1. Magnetic compass
2. Electric fan
3. Relay
4. Microphone