Physics - Generating Electricity

Question 1

Pros and cons of coal

Answer 1

pros - is cheap to make and last longer than oil and gas

cons - has a long start up time and releases GH gases

Question 2

pros and cons of oil

Answer 2

pros - relatively cheap to extract and convert energy

cons - releases GH gases and has a long start up time

Question 3

pros and cons of gas

Answer 3

pros - quick start up time, relatively cheap, slightly cleaner that coal and oil
cons - limited supply, gives off GH gases

Question 4

pros and cons of renewables

Answer 4

pros - don’t produce any GH gases, some have a quick start up time, some are quite cheap
cons - some are expensive, and more criteria is needed to generate renewable. Such as; may spoil landscape, easily damaged (e.g. wave), unreliable, few places in the world where you can build (e.g. geothermal).

Question 5

pros and cons of HEP stations

Answer 5

pros - produces no GH gases, very quick to get instant electricity
cons - expensive to build, dam can ruin environment, often more electricity is needed to pump water back up to higher level than is produced.

Question 6

explain why we need a national grid

Answer 6

to transport electricity all over the country to wherever it is needed

Question 7

describe what step up and step down transformers are used for

Answer 7

changes voltage of electricity so it can be used in homes, hospitals, factories etc. Step up transformers increase voltage and decrease current.

Question 8

describe how the supply and demand for electricity varies and how the NG copes with it

Answer 8

1. it varies throughout different times within 24 hours. For example, the demand will increase after about 5:30am as people are starting to get up.
2. more electricity can be generated at times of the day when there’s a higher demand. For example we can pump water back up to higher resovoirs at HEP stations.

Question 9

explain how power is produced in a fuel based power station

Answer 9

1. boiler burns fuel to heat the water. chemical energy changes to heat energy which changes to kinetic energy.
2. the water is turned to steam is it heats up and the steam is used to rotate the turbine.
3. turbine is connected to a generator which generates the electricity out of movement. kinetic energy becomes electrical.
4. the electricity is either stepped up or down in transformers and transported to people’s homes.
5. the steam is cooled down and turned back into water at the cooling tower.

Question 10

how to calculate efficiency

Answer 10

useful energy output divided by total energy input

multiply by 100 to make a percentage