Question

Question 4
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 1

Option (c) is correct.
One end of the solenoid behaves as a magnetic north pole, while the other behaves as the South Pole. The field lines inside the solenoid are in the form of parallel straight lines. This indicates that the magnetic field is the same at all points inside the solenoid. That is, the field is uniform inside the solenoid. The pattern of the magnetic field associated with the solenoid is similar to the pattern of the magnetic field around a bar magnet. A strong magnetic field produced inside a solenoid can be used to magnetize a piece of magnetic material, like soft iron, when placed inside the coil. The pattern of the magnetic field associated with the solenoid is similar to the pattern of the magnetic field around a bar magnet.