# Properties and Uses of a Magnet

#### Students’ Learning Outcomes

·         Demonstrate that like poles repel each other and unlike poles attracts each other.
·         Investigate that freely suspended magnet always points in the N-S direction.
·         Identify the various uses of magnets and magnetic materials in daily life.

#### Information for Teachers

·         Like poles of magnets repel each other and unlike poles attract each other.
·         Earth behaves like a huge bar magnet with its, north pole in geographical south direction and South Pole in geographical north direction.
·         Hence the north pole of any freely suspended magnet points toward geographic South Pole of the Earth’s magnetic field.
·         A freely suspended magnet always stays along N-S direction.
·         The pole of magnet towards north of Earth is labeled as N and the pole towards south of Earth is labeled as S.

#### Material / Resources

Two bar magnets, thread, stand, a piece of wooden stick, piece of iron wire and copper wire, speaker, electrical bell, textbook

#### Worm up activity

·         Ask the students: What do they think will happen when a bar magnet is freely suspended? Will it come to stay in any direction or in a specific direction?
·         Tell the students to verify their prediction by doing themselves the following activities.

#### Activity 1

·         Call a student at the table in front of the class.
·         Ask him/her to tie a bar magnet with the thread and suspend it from the stand.
·         Call another student and give him another bar magnet.
·         Ask him to show the marked ends of the given magnet as north (N) and south (S) pole to the class.
·         Direct him/her to bring the north pole of the given magnet near to North Pole of the suspended magnet. What happens to the suspended magnet?
·         Now direct him/her to bring the south pole of the magnet near the south pole of suspended magnet. What happens to the suspended magnet this time?
·         Call another student and ask him to bring South Pole near to the north pole of the suspended magnet. What happens to suspended magnet?
·         Similarly, bring the north pole of magnet near the south pole of the suspended magnet and see what happens to suspended magnet. (like poles repel each other and unlike poles attract each other)

#### Activity 2

·         Suspend a lead pencil, an iron rod and a bar magnet with the help of strings from three separate stands.
·         Ask the students to note the positions of the suspended objects.
·         Now call a student and ask him/her to disturb the suspended objects turn by turn and note their positions.
·         Ask the class the following questions:
v  Did all the objects come to rest along their original positions after being disturbed?
v  Does only magnet come to its original position?
(Expected response: Yes only the magnet comes to its original position)
v  Why is it so?
(Expected response: it is due to the Earth magnet, as there is attraction between different poles of magnets)
·         Let some other students repeat the activity and ask about their observations.

#### Activity 3

·         Tell the students that magnets are used in our daily life. We use them in homes, schools and offices. A few of these use are:
v  The tip of screwdriver is made of magnet so that it can keep the screw fixed at same place.
v  The magnet catchers are used to shut the door of the cupboard.
v  Children use magnets to fix some decorative objects on a fridge door.
v  The small magnets are attached to ludo bets to keep their places on iron board.

#### Sum up / Conclusion

·         Like poles of magnet repel each other.
·         Unlike poles attract each other.
·         Freely suspended magnet always stays along N-S direction.
·         Magnets and magnetic materials are used in our daily life.

#### Assessment

·         Verbally ask the following questions to clear the concept:
v  Does a freely suspended magnet change its position when disturb from the original position?
(Expected answer: No, it always points in the same direction)
v  Which poles of the two magnets attract each other?
(Expected answer: opposite poles)
v  Which poles of the two magnets repel each other?
(Expected answer: same poles)