Download Natural Science, Unit 8: Electricity and Magnetism

Natural Science, Unit 8:
Electricity and Magnetism
This slideshow
will tell you
everything you
need to know
from Unit 8 of
Natural Science…
Pay attention!
Insulators
• Insulators are
materials that do not
pass energy through
them easily.
• Examples include:
glass, plastic,
porcelain, rubber and
wood.
• We use insulators to
protect ourselves from
electricity.
• Insulators can also be
called non-conductors.
Conductors
• Conductors are
dense materials
that pass energy
between particles
easily.
• Examples include:
copper, water and
silver.
Benjamin Franklin
• He created the
lightning rod,
which is
important
for modern
society as it
helps to protect
us from being
struck (hit) by
lightning!
• He used a kite and a
Leyden jar (which stored
electrical energy like a
battery) to learn about
electricity.
HANS CHRISTIAN ØRSTED
(1777-1851)
• Hans Christian Orsted
discovered the
relationship between
electricity and
magnetism.
• The unit for
measuring
magnetism- Oerstedis named after him.
• His discoveries led to
the development of
electromagnets.
Electricity
Electricity begins in atoms.
• Atoms are made of protons and
neutrons inside a nucleus.
• Electrons move around outside
the nucleus.
• Protons have a positive
electrical charge.
• Neutrons have no electrical
charge.
• Electrons have a negative
electrical charge.
• Electrons can sometimes move
easily from one object to
another, which results in
objects becoming electrically
charged.
Electricity is the movement
of electrons.
Electrical charges
• Electrical charges repel or attract each other, the same as
magnets.
• Negative charges are attracted to positive ones.
• Negative repels negative and positive repels positive.
Static electricity
• Static means ‘still’ or ‘not
moving’.
• Static electricity is a form of
electricity that doesn’t flow.
• If static electricity forms a
negative charge, it will be
stored in particles until a
positively charged object is
nearby. Then, it will ‘jump’
from negative to positive.
• The electric shock feeling that
you get from a supermarket
trolley or a slide is made
possible by static electricity.
Current Electricity
• When electrons
move from one
object to another,
this creates electrical
current.
• We can trap this in a
circuit using
conductors like
copper or silver
wires .
Electrical Circuits
• Closed electrical circuits
pass the flow of
electrons around in a
circle.
• An electrical circuit has
the following parts:
– A power source provides
energy
– Wires conduct electricity
– A switch opens and closes
the circuit
– A resistor changes the
electricity into different
types of energy
Magnetism
• Can be natural (like
certain minerals) or
man-made, like
electro-magnets.
• Minerals such as
magnetite, iron,
nickel and cobalt are
magnetic.
Types of magnets
• Permanent magnets
never lose their
magnetism
• Induced or
temporary magnets
lose their magnetism
over time
• Magnets have
poles (ends), the
same as planet
Earth- North and
South.
• If you put two
North poles
together, they
will push each
other apart
(repel).
• If you put two
South poles
together, they
will repel.
• If you put North
and South
together, they
will move
towards each
other. This is
called magnetic
attraction.
Magnetic Field
• The liquid iron core of Earth
makes it act like a huge
magnet.
• It creates a magnetic field,
like all magnets, that protects
us from cosmic rays and
protects our atmosphere.
• Some parts of cosmic rays
can enter the atmosphere at
the magnetic North and
South poles. We can see
them as lights- the Aurora
Borealis (North) and the
Aurora Australis (South).
•
•
•
The more magnetic something is, the
bigger its magnetic field will be.
The area around a magnet that
attracts magnetic objects is called a
magnetic field.
We can see a magnetic field by
putting a magnet in an area of
magnetic iron filings.
What things are magnetic?
Magnetic
materials are
always
metallic, but
not all metals
are
magnetic.
• Iron and steel (but not
stainless steel) are magnetic.
• We can make magnets from
other, non-magnetic metals
that are good conductors.
• Electromagnets are magnets
created by passing electricity
through certain types of metal
objects to create a magnetic
field.
Electromagnets
What do we use electromagnets for?
Electromagnets are used in security, trains,
speakers, disks, microphones, hairdryers, TVs,
keycards, bank cards and MRI scanners. These
are just a few examples!