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6 Cards in this Set
- Front
- Back
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What metals can be magnetised?
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Any iron or steel object. Cobalt and nickel can also be magnetised.
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What is the motor effect?
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A force can act on a wire in a magnetic field when we pass a current through the wire.
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How does an electric motor work?
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It uses the motor effect. A simple motor consists of a rectangular coil of insulated wire that is forced to rotate which is connected via two metal or graphite brushes to the battery. The brushes press onto a metal 'split-ring' commutator fixed to the coil.
When a current acts on each side of the coil the force on one side is in the opposite direction to the force on the other side. The split-ring commutator reverses the current every half-turn. Because the sides swap over each turn, the coil is pushed in the same direction every half-turn. |
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What is the generator effect?
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When a potential difference is induced across the end of the wire when it cuts across the magnetic field lines.
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How does a transformer work?
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Alternating current passes through the primary coil, producing an alternating magnetic field. The lines of the alternating magnetic field pass through the secondary coil. This induces a potential difference in the second coil.
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How does a switch mode transformer work?
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It operates at frequencies between 50kHz and 200kHz. It is lighter than a traditional transformer and uses very little power when no electrical device is connected across its output terminals.
It has a ferrite core which is lighter than an iron core and can work at high frequencies. It converts the mains potential difference to a much lower direct potential difference. |
