AQA GCSE Earth Wire(Physics)
Earth Wire
The Earth wire of a circuit, connects the metal case of the appliance to Earth as shown below.
The Earth wire should have a potential difference of 0V.
A current only flows along the earth wire if the appliance becomes faulty.
In the case below the live wire has broken from its contact and is now touching the metal case, so electrical charge is flowing onto the case.
The Earth wire will allow the electrical charges that are flowing onto the case to flow directly to Earth. This prevents the charges building up and prevents someone receiving an electric shock if they touch the metal case.
If a person touches the metal case, and the appliance is not Earthed as shown below:
Then the electrical charge that flowed onto the case from the Live wire has built up. When the person touches the case, the charge flow onto the person and they receive an electric shock!
Double insulated or plastic cased appliances do not need an Earth wire, because their cases are insulators.
Practice Questions
1.What type of case needs an Earth wire?
2.How can an Earth wire protect us from an electric shock
3.Why are Earth wires not needed on double insulated appliances?
Absorption and Emission of EM Radiation
JJ Thomson and Plum pudding model
Ernest Rutherford and the Nuclear Model
Niels Bohr changing the Nuclear Model
Discovering the Proton and Neutron
Measuring radiation from radioactivity
Radiation types and properties
Random nature of radioactive decay
Radioactive contamination or irradiation
Hazards of contamination and irradiation
Studies on the effects of radiation on humans
Different half lives of radioactive isotopes
Nuclear Fission Chain Reaction
Writing nuclear fission equations
Drawing ray diagrams for a concave lens
Drawing Ray Diagram to produce a virtual image for a convex lens
Drawing ray diagram to produce a real image for a convex lens.
Specular and Diffuse Reflection
Seeing Coloured Objects Part 2
Viewing objects through coloured filters
Transparent, Translucent and Opaque