What are the two main ways of finding the shape of a magnetic field?
Plotting them with a compass or using iron filings
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What does it show if the magnetic field lines are closer together?
The magnetic field is stronger
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What is a permanent magnet?
A magnet that cannot be turned off; it has its own magnetic field
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Are electromagnets permanent?
No
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State two factors about the magnetism of iron
Iron is easy to magnetise but loses its magnetism easily, making it perfect for electromagnets
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What is the magnetic material in the centre of the electromagnet called?
The Core
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What would happen if you used steel as a core in an electromagnet?
You wouldn't be able to turn it off because the steel would remain magnetic
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Name the top three factors that will make an electromagnet stronger
Increasing the number of coils in the wire; adding more current to flow through the wire; using a magnetic material for the core
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Which could be stronger: permanent magnets or electromagnets?
Electromagnets
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What kind of magnet might be used to levitate a train?
Electromagnets so that it could be turned off
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What is a relay?
A relay uses a small current in one circuit to operate a switch in another circuit
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True or false: drivers use a relay/electromagnetic switch to turn on the engines in cars
True: car batteries produce very large currents which are dangerous.
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True or false: aluminium will be attracted to an electromagnet
False: aluminium is not magnetic
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True or false: an electromagnet can make a motor
True: you need two magnets and a coil of wire. When you connect the coil to a battery a current flows through the coil. The coil becomes an electromagnet. The forces between the coil and the permanent magnet make the coil spin
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How are objects charged positively or negatively?
By transferring electrons
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What is an electric field?
A region where there is a force on charged particles or materials
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What is electric current?
The amount of charge flowing per second; measured in amps (A) using an ammeter
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What does the potential difference tell you?
The size of the push on the charges and how much energy can be transferred by them. Measured in volts (V) using a voltmeter
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Is the current flowing through a component of high resistance small or big?
Small. Measured in ohms (omega), resistance is calculated using the potential difference across a component and the current through it.
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Which of these has a low resistance: insulators or conductors?
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