3. Three metal elements show magnetic
properties
• Iron
• Cobalt
• Nickel
• Steel
It is an alloy (mixture)
of iron and carbon.
4. Alloy
An alloy is a mixture of two elements, one of which is a
metal. Alloys often have properties that are different to the
metals they contain. This makes them more useful than the
pure metals alone. For example, alloys are often harder than
the metal they contain
5. It has two ends – two poles
North seeking
pole
North pole
South seeking
pole
South pole
15. Materials that are
attracted towards
a magnet
Materials that are
not attracted
towards a magnet
magnetic Non-
magnetic
Magnetic and non-magnetic materials
32. Magnetic induction
•When the steel paper clips gets
attracted to one end of a magnet, it
also becomes a magnet.
•The steel paper clips gets
magnetized by a magnetic field.
•When the paper clip moves away
from the magnet, it loses its
magnetism
33. Groups of particles from which a magnetic material
is made form tiny regions called domains.
34. •If they are arranged at random, it does not behave like a
magnet.
•When the material is magnetised, the domain faces north
in one direction and south in the opposite direction.
37. How to plot a magnetic field instead of using
iron filing
•By using a plotting compass
•Watch video
38. Earth’s magnetic field
• The earth core is made of iron and nickel
• It is divided into two parts: the inner core is made of solid metal and the outer
core made of liquid metal.
• As the earth spins, the two parts of the core move at different speeds and this
generates magnetic field around the earth.
39.
40. • The magnetic north pole originally
got its name because it is the place
to which the north poles of bar
magnets point.
• In reality, it is the Earth’s south
magnetic pole because it attracts
the north poles of the magnet.
• It is similar with the south pole
• However, the old incorrect names
for the magnetic poles are still used.
43. • Hans Christian Oersted is a Physicist who studied
electricity.
• In one of his experiments,
• He was passing an electric current along a wire from a
battery,
• He noticed the movement of a compass needle which
had been left near the wire
• This observation led to many discoveries about how
magnetism and electricity are linked together.
44. • When an electric current passes through a wire, it generates a
magnetic field around the wire.
• A compass can be placed at different positions on a card around the
wire and lines of forces can be plotted.
45. •If the wire is made into a coil and connected into a circuit,
•A magnetic field is produced around the coil.
46. - If a piece of steel is placed inside
the wire coil,
- The magnetism will be stronger.
- When the current is switched off,
steel keeps some of the
magnetism
- It is magnetically hard.
- If a piece of iron is placed inside the
wire coil,
- It makes stronger magnet than
steel.
- When the current is switched off,
iron loses its magnetism completely.
- It is magnetically soft
49. The strength of an electromagnet depends on whether it
has a core of iron.
The other factors that can affect the strength of an electromagnet:
The number of coils affects the number of drawing pins
attracted to an electromagnet.
The size of the current affects the number of drawing pins
attracted to an electromagnet.
53. Using electromagnets – recycling
A large electromagnet is used on a recycling plant
conveyor belt to pick up and move metal cans.
Which metals would the electromagnet
attract?
54. Uses of electromagnets – electric bell
When the circuit is closed, the
electromagnet pulls the
armature towards it, causing
the hammer to strike the bell.
The movement of the
armature breaks the circuit,
and the hammer returns to its
original position.
This sequence repeats,
causing the bell to sound
continuously.
The circuit for a door bell includes an electromagnet.
