Physics (Combined Science) - Paper 2 - Magnetism and Electromagnetism

What are the two types of magnetic pole?
North seeking pole and south seeking pole.
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Where is the magnetic force of a magnet strongest?
At the poles.
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When do poles attract?
When they are unlike/opposite. (e.g. north and south)
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When do poles repel?
When they are like. (e.g. north and north / south and south)
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What is the magnetic field of a magnet?
The region around the magnet, where a force acts on another magnet or magnetic material.
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What are the 3 magnetic materials?
Iron, steel and nickel cobalt.
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The strength of the magnetic field depends on...
...the distance from the magnet.
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What are permanent magnets?
Magnets that produce their own magnetic field.
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What are induced magnets?
They only become a magnet when placed in a magnetic field. The lose their magnetism when removed from the magnetic field.
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The force between a magnet and a magnetic material or induced magnet is always...
...a force of attraction.
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In what direction do magnetic field lines run?
From north to south.
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What is shown by the arrows on the magnetic field lines?
The direction of the force that would act on a north pole placed at that point.
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What is the flux density?
The density of the field lines, (i.e. how close they are together).
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What does the flux density indicate?
The strength of the field at that point. The closer together the lines are, the higher the flux density and thus, the stronger the field.
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What is contained within a magnetic compass?
A small bar magnet.
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What does a compass' needle align with?
The Earth's magnetic field.
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What does a compass' needle point toward?
The magnetic north of the Earth.
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What does this prove?
That the Earth's core is magnetic.
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A magnetic compass can be used to plot the field around a bar magnet. How?
Place the bar magnet on a piece of paper. Place the compass at one end of the magnet. On the paper, mark where the point of the the compass needle is. (continues on next card...)
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continued...
Move the compass so that the tail of the needle is at the previously marked point. On the paper, mark the new point where the needle point is. Repeat and connect the marks until the full field is plotted.
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When is a magnetic field produced around a wire?
Whenever a current flows in a conducting wire.
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The direction of the magnetic field lines around the wire depends on...
...the direction of the current flowing through wire.
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How can you find the direction of the magnetic field lines around the wire?
Using the right-hand grip method.
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What is the right-hand grip method?
Grip the wire in your right hand, with the thumb pointing in the direction of the current. The fingers curled around the wire will point in the direction that the field lines should be drawn.
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The strength of the magnetic field around a wire depends on...
...the size of the current and the distance from the wire.
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What is a solenoid?
A cylindrical coil of wire, acting as a magnet when carrying an electric current.
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What is the effect of a shaping a wire into a solenoid?
The strength of the magnetic field around the wire is increased, creating a strong uniform field inside the solenoid.
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What is a uniform magnetic field?
When magnetic field lines are the same distance apart from each other.
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Why does the solenoid shape increase the wire's magnetic field strength?
It concentrates a longer piece of wire into a smaller area and the looped shape means that the magnetic field lines around the wire are all in the same direction.
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How could you increase the field strength further?
An iron core could be added.
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How can you find the north pole of a solenoid?
Using the right-hand grip method.
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How can you use the right-hand grip method to find the north pole of the solenoid?
Hold the solenoid in your right hand, with your fingers following the direction that the current flows. Your thumb will point to the north pole of the solenoid.
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What is the motor effect?
When a current carrying conductor is placed in a magnetic field, it experiences a force.
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What is the cause of this force, (i.e. what causes the motor effect to occur?)
The motor effect is caused by the field created by the current interacting with the magnetic field.
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How can this forced be increased?
By increasing either the size of the current, the length of the conductor in the magnetic field or the flux density.
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What happens when the direction of either the current or the magnetic field is reversed?
The direction of the force is also reversed.
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How does one calculate the force experienced by the conductor (equation)?
Force (Newtons) = Magnetic Flux Density (Tesla) x Current (Amps) x Length of the wire within the field (metres)
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More cells (higher voltage) produces...
...a bigger current and, therefore, a larger force.
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Stronger magnets produce...
...a higher flux density and, therefore, a larger force.
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Reversing the cell...
...reverses the current and so, reverses the direction of the force.
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Reversing the magnets...
...reverses the field and so reverses the direction of the force.
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Other cards in this set

Card 2

Front

Where is the magnetic force of a magnet strongest?

At the poles.

Card 3

Front

When do poles attract?

Card 4

Front

When do poles repel?

Card 5

Front

What is the magnetic field of a magnet?