P8.2

Question 1

Give some examples of renewable energy resources.

Answer 1

Biofuels (e.g. wood, ethanol, sugar), sun (solar energy), tides, wind, waves, geothermal, water high up (HEP).

Question 2

Give some examples of non-renewable energy resources.

Answer 2

Nuclear (uranium), fossil fuels

Question 3

Why has the use of energy sources increased and the different energy resources changed?

Answer 3

• Population increase
• Different energy resources because such as steam engines, cars, different appliances.
• Electricity generation

Question 4

When people are deciding about energy source usage what do they need to consider?

Answer 4

• Cost
• Environmental effect
• Contribution
• How long the source will last

Question 5

At what frequency and voltage is UK mains electricity in the home at?

Answer 5

50 Hz

230V

Question 6

What is the national grid?

Answer 6

A network of networks and wire and transformers that connects UK power stations to consumers.

Question 7

From the power station to the first transformer, why does is the p.d. so high?

Answer 7

Current is lost if there is a high current as the wires heat up and energy is lost. So a high voltage and low current keeps wastage low.

Question 8

What are the 3 wires in a plug?

Answer 8

Live wire
Neutral wire
Earth wire

Question 9

What is the function of the live wire, its colour and information about its p.d

Answer 9

• Carries voltage
• Alternates between +ve and -ve voltage at 230V
• Brown

Question 10

What is the function of the neutral wire, its colour and information about its p.d

Answer 10

• Completes the circuit
• Electricity flows in through the live wire and out through the neutral wire
• Voltage of 0
• Blue

Question 11

What is the function of the earth wire, its colour and information about its p.d

Answer 11

• There for safety
• Carries current away if something goes wrong, it is connected to earth not the mains.
• Voltage of 0
• Yellow and green

Question 12

What is the p.d. between the live and the neutral wire?

Answer 12

230V

Question 13

What is the p.d between the live and earth?

Answer 13

230V

Question 14

What is the p.d between neutral and earth wire?

Answer 14

0V

Question 15

What is the danger of having metal casing in a home appliance?

Answer 15

• If the live wire becomes loose the appliance casing is live, if you touch it, you will get an electric shock or a fire could occur.

Question 16

How is the danger of having a metal appliance case prevented?

Answer 16

• The casing is connected to the earth wire, the earth wire has a lower resistance than you and the current travels down there to a large pole in the earth.

Question 17

What is the purpose of a fuse?

Answer 17

• A fuse is a thin piece of wire that will melt in the event of excess current being passed through the circuit.
• The fuse melts isolating the circuit and preventing the event of an electric shock from the casing.

Question 18

What prevents the circuits and wiring the in the home from being ‘fried’?

Answer 18

Fuses and earthing

Question 19

What does it mean for an appliance to be double insulated?

Answer 19

Has non-conductive casing (e.g. plastic)

No need for an earth wire to be connected to it