Saturday, 30 March 2013

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

Insulation is covering a live wire with a material that won't conduct the electricity.
Double insulation is a precaution that makes sure the live wire cannot touch the casing (so no shock can be conducted) usually by putting extra insulation round that wire. Double insulation can also mean that the casing of an object is plastic so even if the wire touches it, it wont conduct.
An earth wire is touching the case so that if a current is in the case, it will be directed through the earth wire, this will then take the current to the earth. Additionally the surge of electricity in the wire may break the fuse.
Fuses are sections of wire in the circuit that melt if too high a current goes through them. They come with different maximum currents.
Circuit breakers have an electromagnet that is activated if the current goes above a certain limit. the electromagnet pulls an iron switch towards it, this opens the switch and breaks the circuit.


  1. Thank you for this clear explanation!

  2. Earthing definition - If enough charge builds up on something, electrons may be pulled through the air and cause sparks - which can be dangerous. To prevent charge building up, objects can be earthed: they can be connected to the ground by a conducting material so that the unwanted charge flows away.

  3. The insulation used is mostly plastic

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  5. On my IGCSE Specification list it says describe not undertrained, and for others it has different words, for example, 2.2 says recall on my specification list but on this site it says "understand". This may be because my specification is for 2016, but I did not think that the specification has changed?

    1. It could be the difference of Cambridge, Edexcel & AQA

  6. this is so good! physics is my worst subject and I have next to no notes, but this is really helping me revise! tysm

  7. In double insulation earth wires are not required