Question

The figure shows a circuit containing a coil wound over a long and hollow thin tube. Copy the diagram and show the polarity required by each face of the solenoid.

• A. Current enters the solenoid from face $B$, hence this end of solenoid is south pole and the face $A$ is north pole.
• B. Current enters the solenoid from face $B$, hence this end of solenoid is north pole and the face $A$ is south pole.
• C. None of these
• D. Current enters the solenoid from face $A$, hence this end of solenoid is south pole and the face $B$ is north pole.

Answer 1

Answer: (A)

The polarity of the faces of the coil depends on the direction of current and is obtained by a rule known as "The Clock Rule".

According to this rule "When an observer, looking at the face of the coil, finds the current to be flowing in the anti-clockwise direction, then the face of the coil will behave like the north pole. While if the current is in the clockwise direction, the face of the coil will behave like South Pole.

Hence, the face B behaves like South Pole and face A behaves like North Pole.