# Temporary and Permanent Magnets

#### Students’ Learning Outcomes

·         Demonstrate how magnets are formed and stored.
·         Differentiate between temporary and permanent magnets.

#### Information for Teachers

·         Magnets can be made from magnetic materials by rubbing them with permanent magnets.
·         There is a proper way to store magnets. Soft iron strips called ‘keepers’ are placed across their poles.
·         Temporary magnets are those which lose their magnets property after short time.
·         Permanent magnets are those which retain their magnetic property for long time.
·         Temporary magnets are made from iron.
·         Permanent magnets are formed from steel.

#### Material / Resources

Bar magnets, piece of iron rod, common pins, and iron nails, paper clips, textbook

#### Worm up activity

·         Show two similar thick iron wires to the students; one of which has already been magnetized.
·         Demonstrate the working of the two wires by using them to attract some iron nails.
·         Ask the students, are both of them working as magnets?
(Expected response: No)
·         Then ask the students why does one of the wires work as a magnet while the other doesn’t?
·         Inform them that one of the wires has been magnetized.
·         Inform that an iron wire can be made as magnet by magnetizing it.
·         Now, perform the following activity to show how an iron rod can be magnetized.

#### Activity 1

·         Show two iron rods to the students.
·         Bring the rods close to each other.
·         Ask them, do these rods show attraction?
(Expected response: No)
·         Now place one rod on the table.
·         Rub the rod with one end of the bar magnet starting from one side of the rod towards the other.
·         Repeat this process many times.
·         Now bring the rod near the other rod and ask the various questions like:
v  Do these attract each other now?
v  Has the first rod become a magnet?
(Expected response: Yes)
v  How can magnet be stored?
v  Now tell the students that a magnetic material can be converted into a magnet by rubbing a magnet over it.
v  Allow students in groups to magnetize some iron rods or wires.
·         Inform them that while storing magnets, they should be placed with opposite poles side by side. Two pieces of soft iron should be placed across the poles of the magnets. These are called keepers. A U-shaped magnet can be stored alone using only one keeper.

#### Activity 2

·         Ask the students to take a permanent magnet and repeatedly rub it on the surface of a paper clip/iron nail.
·         Ask them to rub bar magnet on the paper clip/iron nail in one direction.
·         Ask them what happened to paper clip/iron nail.
(Students’ response: It is magnetized)
·         Now ask them to test and record their observation.
(Students’ observations: iron nail attracting paper clip)

#### Activity 3

·         Clamp a strong bar magnet in a horizontal position with a stand.
·         Ask a student to bring a tiny iron nail near its one pole(say N)
·         Ask the students: Does it stick to the magnet?
·         Ask another student to take another iron nail and try to hang it from the first nail.
·         Ask the students why is it pulled by the first nail?
(Students’ response: because the first nail has become a magnet under the effect of strong magnetic force of the magnet)
·         Ask different students to continue hanging nails one by one as could be held by the magnet. It forms a chain of nails.
·         Now hang some steel nails from the other pole of the magnet in the same manner.
·         Now ask a student to remove the iron chain by pulling the top nail away from the magnet. Ask the students: What happened and why?
(Expected response: The iron nails no longer support each other and fall down)
·         Now remove the steel chain from the top and then ask the students: does it collapse too?
·         Ask the students: Why did iron chain collapse and the steel chain do not?
·         Tell the students that iron nails become magnets temporarily. On the other hand, steel nails retain their magnetism and become permanent magnets. So, magnets made by iron are temporary magnets while the magnets made by steel are permanent magnets.

#### Sum up / Conclusion

·         A magnet can be formed by rubbing it with a permanent magnet. This is known as magnetization.
·         The temporary magnet can be formed from an iron bar.
·         The permanent magnet can be formed from a steel bar.
·         Temporary magnets lose their magnetic property in a short time.
·         Permanent magnets retain their magnetic property for a long time.