Posterous theme by Cory Watilo

2.3

2.3 answers

24 November 2010

10:12

• 2.3 describe the uses of insulation, double insulation, earthing, fuses and circuit breakers in a range of domestic appliances

Insulation
· Usually plastic

Double Insulation
· Wire to appliance is insulated
· Appliance casing is insulated
· Examples = computer monitor, plastic kettle, etc

Fuses
· http://www.youtube.com/watch?v=mk0p_zTaFzY
· Made of a thin piece of wire
· When current is too high the wire gets hot and melts
· The fuse "blows"
· UK plugs are fused

Earthing


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Electric toaster - circuit working normally

Live Neutral Earth
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Live Neutral Earth
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Live Neutral Earth
· A large current flows through the metal casing and down the Earth wire
· This melts/"blows" the fuse which breaks the circuit
· This prevents electrical fire

Circuit Breakers
· http://www.youtube.com/watch?v=mKJ5eTJBDyA
· RCD = Residual Current Device
· An RCD can break the circuit much faster than a fuse
· Prevents electric shock

2.3 Build a plug animation

25 November 2011

15:50
>

2.3 Plenary - harder questions

25 November 2011

15:51

PFY p.276, Q.8 a to d only
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