Magnets lose their properties if they are heated or dropped from a height or hit with a hammer.

(i) Like poles (N-N, S-S) repel each other.
(ii) Unlike poles (N-S, S-N) attract each other.

i) Electromagnets are used in electromagnetic trains.
ii) Electromagnets are magnetised when current flows through them. When the direction of current is changed, poles will be changed.
iii) Magnets are attached at the bottom of the train and rail tracks.
iv) The train is lifted from track upto 10 cm height by the property of some poles that repel each other.
v) By using attraction and repulsion at the same time between the magnets in tracks and bottom of the train it moves forward.
vi) The magnets are controlled by electricity.
vii) There is no friction. So the train can easily attain a speed of 300 km/h.

i) Place the iron needle on a table. Now take a bar magnet and place one of its poles near one edge of iron needle and rub from one end to another end without changing the direction of the pole of the magnet. Repeat the process for 30 to 40 times.
ii) Bring a pin or some iron filings near the iron needle to check whether it has become a magnet. Does the iron needle attract the pin / Iron filing? If not continue the same process for some more time.

If we keep a strong bar magnet above the glass of water, all pins inside the water will come up due to its attraction towards the magnet.

Opposite poles, attract each other. Second pole of magnet A is N (North Pole). So magnet B has S-N poles. Then only they will attract.

a) When we place the bar magnet near the iron filings large amount of iron filings stick on the two ends of the bar magnet. These ends are poles of the magnet.
b) Poles will attract more iron filings, because poles have high magnetic strength.