13. Mains electricity

Question 1

Describe what a ‘fossil fuel’ is.

Answer 1

The remains of dead plants and animals that have stored the sun’s energy from millions of years ago.

Question 2

Name 3 examples of fossil fuels

Answer 2

Coal, oil and natural gas

Question 3

How are fossil fuels formed?

Answer 3

Dead plants and animals are subjected to pressure and heat over millions of years.

Question 4

Describe the four stage of coal formation.

Answer 4

1. Ferns and forests grew in wetlands and died.
2. Over time the layers of rotting material were pressurized and form peat.
3. Sand and water collected and pressed down to form lignite.
4. The heat inside the earth turned to lignite to coal.

Question 5

What are non-renewable resources.

Answer 5

Resources like fossil years that have taken millions of years to form and will eventually run out and cannot be replaced.

Question 6

What is the most common fossil fuel in SA used in power stations?

Answer 6

Coal.

Question 7

Explain briefly how a coal-fired power station works

Answer 7

Coal is burned to heat water. The steam is put under pressure and then used to turn a turbine which then turn a generator to produce electricity.

Question 8

What does a transformer do?

Answer 8

Increases or decreases the energy (voltage) carried by the electricity.

Question 9

What do the sub-stations do that we see around Pinelands?

Answer 9

They decrease the voltage (energy) of the electricity coming from power stations so it is safe to use in our houses.

Question 10

Why is electricity expensive to produce?

Answer 10

The infrastructure is expensive (coal, power station, transmission network, transformers)

Question 11

What does the power rating of an electrical appliance tell us?

Answer 11

The rate at which the appliance uses electrical energy.

Question 12

What unit is power measure in?

Answer 12

Watt (W)

Question 13

What unit of electricity do we measure consumption in?

Answer 13

Kilowatt hour (kWh). This is equivalent to a 1000W (1kW) appliance (like an iron) being used for 1 hour.

Question 14

How do solar heaters/geysers save electricity.

Answer 14

Water is partly heated using the energy from the sun and thus less electricity is used to heat water.

Question 15

What is an illegal electricity connection?

Answer 15

A connection to the electricity supply that has not been made by a qualified electrician according to the electricity laws.

Question 16

Why are illegal connections dangerous?

Answer 16

They are often unsafe and can cause harm.

Question 17

What are renewable energy sources?

Answer 17

Energy sources that will not run out like wind, solar and moving water.

Question 18

Describe a hydro-electric power station.

Answer 18

Water from a high dam runs downhill and drives a generator to create electricity.

Question 19

What are photovoltaic (PV) cells?

Answer 19

Solar panels that convert sunlight into electricity.