Magnets

Magnets Topic as per the Primary level & middle school level.

1. Magnets
By –SumanTiwari
(M.Sc, M.Ed.)

2. What is a Magnet?
•A magnet is an object made of iron or steel. It
can interact with some objects. Without
touching the object, it can attract(pull) an
object or repel(push) an object

3. Based on its shape magnets are of various types
Typesof magnets

4. Magnets are classified into two groups based on
how they achieved their magnetism and for how
long they retain their magnetic abilities:
1.Natural magnets
2.Artificial magnets/Man made magnets
Note:Thereare three types of magnets and they are as follows:
•Permanent magnet
•Temporary magnet
•Electromagnets
Typesof magnets

5. •Natural magnets –Natural magnets occur in
nature and have a weak magnetic field.
Lodestones are a common example of natural
magnets.
Typesof magnets

6. •Artificial magnets –Artificial magnets can be
produced by man-made means and have a
stronger magnetic field. They can also be shaped
as required. When an artificial magnet is shaped
in the form of a bar, it is called abar magnet.
Typesof magnets

7. Characteristics of a
magnet:
1. It attracts magnetic materials.
Materials are of two types:
Magnetic Non-magnetic
Iron and Steel
Wood and
Plastic

8. •Magnetic materials: Objects that are attracted to
magnets are called Magnetic materials.
•Non-magnetic materials: Objects that are not
attracted to magnets are called non-magnetic
materials.
Typesof materials

9. Canyou think of 3 other materials that are
magnetic and non-magnetic?
Lets Predict…Activity 1

11. 2. It has two poles where attraction is the
strongest.
A magnet has two poles. They are called the
North pole and the South pole
Characteristics of a
magnet:

12. 3. Unlike poles attract and like poles repel.
Characteristics of a
magnet:

13. Lets Predict…Activity 2

14. 4. It comes to rest in the North-South direction
when freely suspended.
The Earth acts like a giant magnet with its own
North and South poles. The magnetic effect of
earth interacts with a freely suspended magnet,
causing the magnet to point in the North-South
direction.
Characteristics of a
magnet:

15. Thischaracteristic of a magnet allows it to be
used to make compasses.
Video link:
https://edpuzzle.com/media/5e9401322e842
13f0fc1855b

16. Characteristics of a
magnet:
•To make a compass using easily available materials:
•Video Link:
•https://safeYouTube.net/w/SAe8
•https://safeYouTube.net/w/KBe8

17. Whatare some uses of
magnets in everyday
objects?
•Magnets are used for constructing magnetic
needles and mariner’s compass.
•Permanent magnets find applications in
generators, electric accelerators, and electric
motors.
•Electromagnets find application in speakers,
electric bells, and electric cranes.

18. •Magnets are used in filtering machines which
separates metallic ores from crushed rocks.
•It is also used in food processing industries for
separating small metallic pieces from grains etc.
•Magnets are used in MRI machines which are
used to create an image of the bone structure,
organs, and tissues. Even magnets are used to
cure cancer.
Characteristics of a
magnet:

19. •At home, you use magnets when you stick a paper on
the refrigerator in order to remember something.
Attaching a magnetic bottle opener to the fridge can
come in handy.
•We often use pocket a compass to find out directions
when we are on a trek. The pocket compass uses a
magnetic needle to point north.
•The dark strip on the back of debit and credit cards is of
magnetic nature and are used to store data just like
computers’ hard drives.
•Magnets can help collect all the nails which are scattered
on the ground after a repair job.
Characteristics of a
magnet:

20. •Magnets are used inside TVs, Sound speakers
and radios. The small coil of wire and a magnet
inside a speaker transforms the electronic signal
to sound vibrations.
•Magnets are used inside a generator to
transform mechanical energy toelectrical
energywhere there are other kinds of motors
which use magnets to change electrical energy
to mechanical energy.
Characteristics of a
magnet:

30. Making Magnets

31. •Stroke Method
•Electrical method
•When a magnetic object becomes a magnet ,
we say that it is magnetised.
Methodsto make a
magnet

32. •Stroking a magnetic object with a strong magnet
will turn it into a magnet.
•To magnetise an iron nail using the stroke
method:
•Step-1Stroke the iron nail a few times with one
end of a bar magnet as shown in the diagram
below. Remember to stroke the iron nail in the
same direction with the same pole of the
magnet each time.
Strokemethod

33. •Step-2
•Test to see if the iron nail can attract any small
magnetic object.
•Step-3
•Continue to stroke the iron nail until it becomes
a magnet.
Strokemethod

34. •We can also make a magnet using electricity. To
magnetise an iron nail using the electrical
method.
•Step-1
•Coil a long piece of wire around the iron nail at
least 20 times.
•Step-2
•Connect both ends of the wire to a battery.
The electricalmethod

35. •Step-3
•Test to see if the iron nail can attract any small
magnetic object.
•A magnet made using electricity is called an
electromagnet
The electricalmethod

36. •Some materials -like iron, cobalt or nickel -have
little groups of atoms in them that behave like
magnets. These groups of atoms are
calledmagnetic domains.
•In unmagnetised materials, the magnetic
domains are arranged randomly and point
indifferent directions, cancelling each other out.
In magnetised materials, the domains are
aligned in such a way that they all point inthe
same direction. The better the alignment is, the
stronger the magnet.
•
Magneticdomains

37. The diagram below shows the alignment before and
after magnetising a piece of metal:
Magneticdomains

38. •The reason an unmagnetised nail is attracted to
a magnetic piece of iron is that more domains in
the nail line up when it is placed near the
magnet. When the magnet is removed, most
domains return to a random arrangement and
the nail becomesdemagnetised.
•Innon-magnetic materialsthe domains remain
in a random arrangement, even when placed in
a magnetic field.
Demagnetisation

39. Magnetism can also be removed in a number of
ways:
•Drop or hammer the magnet; this reduces the
alignment and the magnetism
•Heat the magnet
•Stroke one magnet with another in different
directions. This works better for demagnetising
weaker magnets.
Demagnetisation

40. Let’s Try-Activity

43. atoms

50. Thank You