Question

The adjacent diagram shows a small magnet placed near a solenoid AB with its north pole N near the end A. Current is switched on in the solenoid by pressing the key K. State the polarity at the ends A and B:

• A. A - south pole, B - north pole
• B. A - south pole, B - south pole
• C. A - north pole, B - north pole
• D. A - north pole, B - south pole

Answer 1

The correct option is A A - south pole, B - north pole

The polarity of the magnetic field (that is, which end is magnetic-north or magnetic-south) can easily be found from the Right hand thumb rule. If we hold the device in our right hand, so that the fingers curl around it in the direction of the conventional current flow, then the thumb will point to the north pole of the magnet. Also, a solenoid when suspended freely aligns itself in the north-south direction, thus behaving like a magnet. One end of the solenoid acts like a north pole and the other end the south pole.

Hence, A - south pole, B - north pole.