When a hole is cut at the center of the bar magnet, then the pole strength of the bar magnet will:

When a hole is cut at the center of the bar magnet, then the pole strength of the bar magnet will: Correct Answer Remain unchanged

CONCEPT:

Magnet:

• An object which is capable of producing a magnetic field, attract Ni, Co, Fe, etc, and align in the geographical north-south direction when suspended freely is called a magnet.

Pole strength:

• The strength of a magnetic pole to attract magnetic material towards itself is known as pole strength.
• It is a scalar quantity.
• Its SI unit is amp×m.

Poles of magnet:

• The point on the magnet which has maximum attraction property is called the poles of the magnet.
• The poles of the magnet lie slightly inside from the end.
• If a magnet is cut perpendicular to its axis then its pole strength does not change.
• If a magnet is cut along its axis then its pole strength decreases.
• If a magnet is cut into two equal parts along its length then the pole strength of each part becomes half of the given original magnet.

EXPLANATION:

• The point on the magnet which has maximum attraction property is called the poles of the magnet.
• The poles of the magnet lie slightly inside from the end.
• When a hole is cut at the center of the bar magnet its end remains unaffected where the poles of the magnet lie.
• So the poles of the magnet remain unaffected when a hole is cut at the center of the bar magnet, so the pole strength of the bar magnet will remain unchanged. Hence, option 3 is correct.