p.8.2

Question 1

what are the main energy sources used on earth

Answer 1

fuels - biofuels, nuclear fuels and fossil fuels 
sun
tide
rivers
wind 
waves 
geothermal

Question 2

what are the main used of energy sources

Answer 2

heating, transportation and generating electricity

Question 3

what heating and electric alternatives are there that don’t burn fossil fuels?

Answer 3

build house that maximise heat from the sun
heat water in panels that go on top of roofs.

solar panels and wind turbines, biofuels, steam from hot rocks

Question 4

what are the main reason energy fuel demands have changed over time

Answer 4

population has grown from 1 to 7 billion

change in technology that require fuels

Question 5

state some issues with energy supply

Answer 5

the demand for energy will increase as more countries become developed
the fossil fuels are running out
burning fossil fuels produce a large amount of carbon dioxide which increases global warming

Question 6

what 4 things need to be considered when choosing an energy supply

Answer 6

cost
effect on environment
contribution to climate change
how long the source will last

Question 7

what is the national grid

Answer 7

this is the network of power stations, under ground wires, transformer and pylons used to get electricity to everywhere around the country

Question 8

how are transformers used in the national grid

Answer 8

transformers step up and step down the voltage on the national grid so that the wires don’t get too hot. when the transformer step up the voltage its at 400,000 volts they then step it down to 230 volts so it can be used in homes

Question 9

what is the ‘mains’

Answer 9

this usually means the mains voltage which is 230 volts. the stations produce an alternating current with a frequency of 50 hz

Question 10

what it the difference between direct voltage and alternating voltage

Answer 10

direct = current is not oscillating 
alternating = oscillating

Question 11

what are the three wires in a plug and what do they do

Answer 11

live wire : brown
neutral wire : blue, this wire and the live wire make a full circuit.
earth wire : connected to the earth normally by a long metal pole outside of your house

Question 12

state some safety features of the plug

Answer 12

if the live wire becomes loose the I can touch the metal casing. if this happens the casing becomes ‘live’. if someone touches it the current will pass through them. to prevent this the earth wire connects to the case and the current goes straight to the earth.
alternatively the case can be made of plastic