Physics - Magnetism

• Created by: Jasmin3
• Created on: 15-04-18 19:02
What are the two poles on a magnet?
North and South
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What do all magnets produce? What is ths?
A magnetic field, where all other magnetic materials experience a force.
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How are magnetic fields shown?
With magnetic field lines always going from North to South.
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The closer the magnetic field lines are the _____ the mangetic field is.
stronger
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Where is the magnetic field strongest?
At the poles of the magnet.
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If two poles are put near each other they will exert a force, in which two ways can this force act?
It can attract or repel the magnet.
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Which direction does a compass point in?
Towards the magnetic field.
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When a compass is not near a magnet where does it point and why?
Towards North because Earth generates it's own magnetic field inside the core.
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What is a 'permanent' magnet?
One that produces it's own magnetic field.
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What is an 'induced' magnet?
Magnet materials that turn into magnets when put in a magnetic field.
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What happens if you take a magnetic field away from an induced magnet?
They lose their magnetism and stop producing a magnetic field.
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What is the force between a permanent and induced magnet?
Always attractive.
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When a current moves through a wire, what happens?
Concentric circles make up a magnetic field perpendicular to the wire.
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How do you use the right-hand Thumb rule?
Point your thumb in the direction of the current and curl your fingers round - direction of your fingers is the direction of the magnetic field.
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The larger a current through a wire or the ____ to the wire you are, the _____ the field is.
closer, stronger
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What does a solenoid do?
It increases the magnetic field by wrapping the wire into a coil.
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How does a solenoid work?
The field lines around each wire line up, this means field lines pointing in the same direction, very closely, meaning a stronger field.
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What is the force like outside a solenoid?
Outside the coil, the field is like a bar magnet.
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How can you increase the field strength of a solenoid?
Put a block of iron in the centre because it becomes an induced magnet whenever current is flowing.
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A solenoid with an iron coil, which can be switched on and off is better known as what?
An electromagnet.
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Give 2 uses of an elctromagnet.
In circuits - as switches. In cranes- high magnetism allows it to pick up scrap yard materials.
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What happens when a current-carrying wire is put between magnetic poles?
The magnetic field around the wire interacts with the magnetic field and causes the magnet and conductor to exert a force on each other.
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In The Motor Effect, to experience full force, where must the wire be? Why?
9o degrees to the magnetic field, if it runs parallel no force is exerted.
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How would you show direction of force with a horse shoe magnet?
Apply current to a set of rails inside the magnet. Place a bar at the end of the rails, completing the circuit, it generates a force which rolls along the bars.
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What 2 factors effect strength of the force?
Strength of magnetic field and amount of current.
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What is magnetic flux density?
How many field lines there are in a region.
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What is the formula for magnetic flux density?
Force (N) = Magnetic Flux Density (Tesla) x Current (A) x Length (M) F=BIL
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Explain how to use the left hand rule.
Thumb points in direction of the force (motion). First finger points in the direction of the field. Your second finger points in the direction of the current.
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Why does a current-carrying coil rotate in a magnetic field?
Because the coil is on a spindle, the forces act one up, one down causing it to spin.The split-ring communicator swaps the contacts every half turn to keep the motor rotating in the same direction.
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How could you reverse the direction of the motor?
Swap the polarity of the dc supply or swap the magnetic poles over.
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What effect causes loud speakers to work?
The Motor Effect
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Explain how a loud speaker works.
An (ac) is sent through a coil of wire attached to a paper cone. The coil surrounds one pole of a permanent magnet is surrounded byy the other pole so the force acts on the coil.When the current reverses the force acts in opposite dircetions.
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Other cards in this set

Card 2

Front

What do all magnets produce? What is ths?

Back

A magnetic field, where all other magnetic materials experience a force.

Card 3

Front

How are magnetic fields shown?

Card 4

Front

The closer the magnetic field lines are the _____ the mangetic field is.

Card 5

Front

Where is the magnetic field strongest?