For a current in a long straight solenoid N- and S-poles are created at the two ends. Among the following statements, the incorrect statement is:
(a) The field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid.
(b) The strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the coil.
(c) The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet.
(d) The N and S-poles exchange position when the direction of current through the solenoid is reversed.
Answer:
Properties of magnetic field produced in a solenoid:
- A solenoid behaves like a bar magnet when current is passed through it.
- The field lines are parallel straight lines inside a solenoid which indicates that the magnetic field is uniform inside a solenoid.
- Magnetic field produced in a solenoid is very strong and hence they are used to make electromagnets.
- When direction of current is reversed i n a solenoid, the north and south poles are exchanged.
Checking the options:
- (a) The field lines inside the solenoid are in the form of straight lines which indicates that the magnetic field is the same at all points inside the solenoid - This is correct.
- (b) The strong magnetic field produced inside the solenoid can be used to magnetise a piece of magnetic material like soft iron, when placed inside the coil - This is correct.
- (c) The pattern of the magnetic field associated with the solenoid is different from the pattern of the magnetic field around a bar magnet - This is incorrect, because a solenoid behaves like a bar magnet when electricity is passed through it.
- (d) The N and S-poles exchange position when the direction of current through the solenoid is reversed - This is correct.
So, the correct answer is (c)
