Transcript Learning Objectives

Generators
• To explain how a generator works
to produce electric current.
• To explain the difference between
alternating and direct current.
Producing Electricity
• Electricity is produced by generators.
Key Terms You need to
Understand!
• Electricity is the flow of charged
particles called electrons.
• Current is the rate of flow of electrons.
• Voltage is the push of electrons – it
measures the amount of energy at a
given point.
How a generator works
• You need three things for a
generator to work:
–A magnet
–Coils of wire
–Movement
Producing electricity…
• Moving a piece of wire in a magnetic
field causes an electric current to flow
through the wire.
• This process is called electromagnetic
induction.
• Current produced this way is called an
induced current.
AUTO
Electromagnetic Induction
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● increasing the strength of the magnet
● increasing the number of turns in a coil
● increasing the speed of the magnet
coil of insulated wire
permanent magnet
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You can get the same effect by
moving the wire and keeping the
magnet still.
How current can be
increased…
• Adding more turns on a coil of wire
• Using stronger magnets
• Moving the wire faster
Direction of current
• The direction of current can be
changed by changing the
direction…
–Of the movement of wire
–Of the magnetic field
Dynamos
A dynamo is a particular type of
generator which is often used on bikes to
power lights. Here the magnet is rotated
instead of the coil. They dynamo is
attached to a wheel so as you turn the
wheels, your turning inside the dynamo.
Dynamos
• Current produced in
a simple dynamo can
flow in two ways, if
it flows in the same
direction and is
called direct
current (DC).
• If it flows and
keeps changing
direction it is called
alternating
current(AC).
Generators
• In a generator wire
goes up and down
within the magnetic
field.
• This causes the
induced current to
change direction.
• Current that
changes direction
like this is called
alternating current
(AC).
Generators in Power
Stations
• Generators in power stations produce a
lot of energy and need to induce a strong
voltage.
• To do this, electromagnets are used
instead of permanent magnets, which are
expensive.
• Electromagnets are stronger magnets
which can be switched on and off.
Question
1. Put more turns of wire on the coil, spin
the coil faster, use stronger magnets
2. They need to generate large currents,
so they need powerful magnets and
electromagnets are stronger than
permanent magnets.