P8.2

Question 1

what are renewable resources

Answer 1

Resources that will not run out on a timescale of millions of years

Question 2

What are non-renewable resources

Answer 2

Resources that take millions of years to form.

Question 3

Non renewable energy resources that are fuels

Answer 3

Nuclear fuels (e.g uranium)
Fossil fuels (e.g coal, oil and gas)

Question 4

Renewable energy resources that are fuels

Answer 4

Biofuels (that come from living material, such as wood, ethanol from sugar, or methane from sewage.)

Question 5

Alternatives to using fossil fuels for heating

Answer 5

. Build houses that maximise heating by the sun
. heat water using a solar water heating system that contains water in pipes on your roof called a solar panel
. Heat your house with water from beneath the ground

Question 6

Different energy sources for heating

Answer 6

. Using geothermal energy
. Using solar cells

Question 7

What happened during the industrial revolution

Answer 7

People started to use coal in machines, factories and for transport. From about 1920 there has been a huge increase in oil usage as people use it for cars and planes (transport).

Question 8

Issues with the energy supply

Answer 8

. Increased demand for electricity with a developing world
. The supply of fossil fuels is finite and will eventually run out
. Burning fossil fuels or biofuels increase CO2 which contributes to the greenhouse gas effect and climate change

Question 9

What do individuals and the government need to consider when deciding about energy sources to use

Answer 9

Cost ( to set up and to remove)
effect on the environment (pollution and visual pollution)
Contribution to climate change
how long the sources will last

Question 10

What is the national grid

Answer 10

The national grid are the power stations, transformers, grid network ( underground wires and wires on pylons), and transformer substations.

Question 11

How are transformers used in the national grid

Answer 11

Transformers change the potential difference to reduce the heating effect making the national grid an efficient way to distribute electricity.

Question 12

What do step up and step down transformers change the voltage to.

Answer 12

Step up - 400,000 V
Step down - 230 V

Question 13

Equation relating voltage and current across primary and secondary coils

Answer 13

Vp x Ip = Vs x Is

Question 14

How does current relate to heat

Answer 14

As current increases the heat increases. Heat also depends on the resistance of the wires

Question 15

Power wasted formula

Answer 15

p = I (squared) x r

Question 16

What do u need to do to compensate for the power waster

Answer 16

You need to supply much more power which means more fuels (fossil fuels) are burnt in power stations.

Question 17

What is mains voltage

Answer 17

The domestic power supply

Question 18

What is the voltage and frequency of mains voltage

Answer 18

It is 230 V and 50Hz

Question 19

Is mains electricity dc or ac

Answer 19

It is ac

Question 20

What colours are the different wires in a plug

Answer 20

Brown - live wire
Green and yellow - earth wire
Blue - neutral wire

Question 21

What happens if the live wire is loose

Answer 21

The live wire being loose inside an appliance means that it can touch the metal casing making it go live. This means that if you touch it you will have a 230 V potential difference across you because you are connected to earth and a dangerous current can flow through you.

Question 22

How is this prevented

Answer 22

This is prevented by using an earth wire connecting the case to ground so that current flows through the earth wire and not you. Also the wire inside the fuse melts and switches off the circuit.