Chapter 4 - Generating Electricity

Question 1

How is energy released from uranium

Answer 1

Nucleus of uranium undergoes nuclear fission

Question 2

Advantage and disadvantage of nuclear power stations compared to fossil fuel power stations

Answer 2

Advantage:
•Much more energy is released per kg or ur soul undergoing fission reactions that from each kg of fossil fuel burnt
•Nuclear power stations do not release any greenhouse gases

Disadvantage:
•Nuclear power stations produce radioactive waste that must be stored for a long period of time

Question 3

What fuel is used in nuclear power stations

Answer 3

Uranium

Question 4

What is a biofuel

Answer 4

A fuel obtained from living or recently living organisms. They are renewable resources

Question 5

What process does the nucleus of a uranium atom undergo

Answer 5

Nuclear fission

Question 6

How does a wind turbine work

Answer 6

Wind passing over blades makes them rotate and drives a generator at the top of the tower

Question 7

How does hydroelectric power work

Answer 7

At hydroelectric power station, water is collected in a reservoir. Water is allowed to flow downhill and turn turbines at bottom of hill.

Question 8

What happens in a pumped storage system

Answer 8

At times of low demand surplus energy is used to pump the water back up the hill to the top of the reservoir. This means energy can be stored. Then at times of high demand the water can be released to fall through the turbines and transfer the stored energy to electrical energy

Question 9

How does wave power work

Answer 9

Movement of waves drives a floating turbine that turns a generator. Electricity is delivered to the grid system on a shore by a cable.

Question 10

How does tidal power work

Answer 10

If a barrage is built across a river estuary, the water at each high tide can be trapped behind it. When the water is released to fall down to the lower sea level, it drives turbines

Question 11

What does solar energy travel as

Answer 11

Electromagnetic radiation

Question 12

What does a solar cell do

Answer 12

Transfer solar energy into electrical energy

Question 13

How does a solar power tower work

Answer 13

Uses thousands of mirrors to reflect sunlight onto a water tank to heat the water and produce steam

Question 14

How is geothermal energy produced

Answer 14

It is produced inside the earth by radioactive processes and this beats the surrounding rock. In volcanic or other suitable areas, very deep holes are drilled and cold water is pumped down to the hot rocks. There it is heated and comes back to the surface as steam. The steam is used to drive turbines that turn generators and electricity is produced

Question 15

How could carbon dioxide be captured so that it isn’t released into the atmosphere

Answer 15

Storing it in old oil and gas fields

Question 16

What are the disadvantages of nuclear energy

Answer 16

It produces hazardous nuclear waste, which is difficult to dispose of safely

There is also a small risk of a big nuclear accident

Question 17

What are the disadvantages of wind power

Answer 17

Requires many large turbines

Not reliable as wind does not always blow

Question 18

What are the disadvantages of falling water

Answer 18

Only works in wet and hilly areas

Damming the areas causes flooding and affects local ecology.

Question 19

What are the disadvantages of wave power

Answer 19

Can be hazardous to boats

Question 20

What are the disadvantages of solar power

Answer 20

Solar cells only produce a small amount of electricity

Unreliable

Question 21

What are the disadvantages of tidal power

Answer 21

Only a few river estuaries are suitable

Building a barrage affects the local ecology

Question 22

What are the disadvantages of geothermal energy

Answer 22

Only economically viable in very few places

Drilling through a large depth of rock is difficult and expensive

Question 23

What are the disadvantages to all renewable sources

Answer 23

They are unreliable (apart from tidal)

Question 24

What are the advantages of overhead cables compared to underground cables

Answer 24

They are easier to repair and are cheaper

Question 25

What is the mains voltage in homes

Answer 25

230V

Question 26

Why are step up transformers used

Answer 26

Because transmissions at high voltage reduces the energy wasted in the cables, making the system more efficient.

Question 27

Why are step down transformed used

Answer 27

To reduce the voltage to 230 V for use in homes and offices as supplying electricity to consumers at very high voltages would be dangerous.

Question 28

What is the base load demand

Answer 28

The constant amount of electricity provided by nuclear, coal fired and oil fired power stations.