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igcse physics notesprinted 102 · PDF 102
124 pagesrevision 46936
printed 102 · PDF 102
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102
the circuit.
● Fuses have a current rating which should be slightly
higher than the current used by the
device in the circuit. The most common are 3A, 5A and 13A.
Circuit breakers:
● Circuit breakers consist of an automatic electromagnet switch which
which breaks the
circuit if the current rises over a certain value.
● This is better than a fuse as it can be reset and used again, and they
operate faster.
Earthing metal cases:
● Earth wires creates a safe route for current to flow through in the case of
a short circuit,
preventing electric shocks.
● Earth wires have a very low resistance so a strong current surges
through them which
breaks the fuse and disconnects the appliance.