PHYSICS [2 Mark Question Answer]

A freely suspended magnet always rests in the north-south direction because the north pole of the magnet lies in the geographic north direction and the south pole of the magnet lies in the geographic south direction. So it aligns itself in N-S direction. Unlike poles attract and like poles repel.

If we suspend a magnet such that it is free to swing, we see that it always rests in the north-south direction. The north pole of the magnet lies in the geographic north direction and the south pole of the magnet lies in the geographic south direction. So it aligns itself in N-S direction.

A magnet can be demagnetized in the following ways:

1. rough handling
2. hammering the magnet several times.
3. passing an alternating current around the magnet.
4. dropping the magnet on the floor several times.
5. heating the magnet to a very high temperature.

Magnetic substances: The substances that get attracted by a magnet are called magnetic substances.
e.g. Iron, steel, cobalt, and nickel are magnetic substance
Non-magnetic substances: The substances that do not get attracted by a magnet are called non-magnetic substances,
e.g., wood, plastic, copper, paper, aluminum, rubber, stone.

Use of magnet:

1. Magnets are used in magnetic compass, doorbells, refrigerators.
2. Magnets are used in dynamos, motors, loudspeakers, microphones, etc.
3. Ceramic magnets are used in computers.
4. Magnets are used in toys to give magic effects.

Take the given iron bar AB. Wound several turns of insulated copper wire over the bar. Connect the ends of the wire to a battery through a switch. Press the switch to pass current. After some time, the bar AB becomes a magnet.

The end A of the bar at which the current enters the coil in clock¬wise direction becomes the south pole (S) and the end B of the bar at which the current leaves the coil in anti-clockwise direc¬tion becomes the north pole (N).

When magnets are not in use they should be kept and stored in magnetic keepers. The magnetic keeper is a piece of soft iron. A magnetic keeper has cardboard with one or two iron soft pieces. Two magnets are placed in such a way that their opposite poles are close to each other and then a soft iron keeper is attached to it.

Take a bar magnet and place a steel pin at some distance. We observe that nothing happens. Now, bring the steel pin near the pole of the bar magnet. We notice that pin sticks to the magnet. This experiment shows that the maximum magnetic force acts at the poles of the magnet.

A magnet can be demagnetized in the following ways :

1. rough handling
2. hammering the magnet several times.
3. passing an alternating current around the magnet.
4. dropping the magnet on the floor several times.
5. heating the magnet to a very high temperature.

Magnets must be handled with care or else they lose their magnetic properties and become weak. To prevent a magnet from becoming demagnetized, the magnet should not be handled roughly, hammered, dropped, heated. It should be stored using magnetic keepers.

Magnetic poles always exist in pairs and cannot exist independently. If a bar magnet is broken into two or more pieces, each of them will have a north pole and a Southpole. Hence, it is impossible to obtain a piece of the magnet with only one magnetic pole.