Download Michael Faraday, one of the great British physicists, in 1831

Michael Faraday, one of the great British physicists, in 1831
discovered a way to generate an electric current without using a
battery.
The principle of electro-magnetic Induction which is used in
generators and transformers allows electricity to be generated
on a large scale.
Look at the following demonstration
and describe what is happening.
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Draw on the following diagram some magnetic field lines
between the poles of the magnet.
Describe and explain what happens to the needle on the galvanometer
when the wire is moved in the following ways:
Moved vertically (A
→ B, B → A)
Moved Horizontally ( C
→ D, D → C)
(a) Draw the magnetic field around the bar magnet.
(b) Describe what happens in this demonstration
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(c) Describe three ways in which the size of the induced current could be
increased.
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(d) Describe what would happen if the magnet were repeatedly moved into
and out of the coil.
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1. The diagrams below each show a wire connected to a sensitive ammeter.
The wire is placed in a magnetic field between opposite poles.
For each diagram draw the meter reading you would expect to see. The first
one has been done for you.
2. For each diagram below describe the motion of
the magnet compared to diagram A on the left. You
should use the following words:
‘Same speed’
‘Faster’
‘Opposite direction’
‘Slower’
‘Same direction’
‘No movement’
When a wire cuts the magnetic field lines a current is made to flow in the
wires. The direction of the current in the wire can be predicted using
Fleming’s right hand rule for generators.
In order to predict the direction of the current you need to know two things:
 The direction of the magnetic field lines,
 The direction of the motion of the wire in the field.
Example
The wire AB is part of a complete circuit and is made to cut upwards through
the magnetic field between the poles.
A
B
Use the above rule to work out the direction of the current along the wire.
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 When a wire cuts magnetic field lines a voltage is induced which
drives a current.
 A larger voltage is induced when:
 more wire or more coils cut the magnetic lines,
 the magnetic field lines are cut faster.
 there is a stronger magnetic field.
 The direction of the current in a wire can be found using Fleming’s right
hand rule for generators.
1. The following dynamo can be attached to the back wheel of a bicycle in
order to generate electricity to power a light.
Briefly describe how the bulb is made to light up as the bicycle wheel turns.
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2.
3. Use Fleming’s Right-hand rule to predict the direction of the current in the
wire in the following diagram.
A
B
Current flows in the
direction:
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4. Use Fleming’s Right-hand rule to find the direction of the current in the
wire in the following diagrams.
Use an arrow on the wire to show the current flow.
(a)
(b)
(c)