P5 - Mains electricity

Question 1

What is DC

Answer 1

Direct Current - flows in one direction

Question 2

What is AC?

Answer 2

Alternating current - repeatedly reversed direction of current

Question 3

National grid?

Answer 3

Travel of electricity throughout the country with different energy devices

Question 4

What colour is the live wire?

Answer 4

Red

Question 5

What colour is the neutral wire?

Answer 5

Blue

Question 6

What colour is the earth wire?

Answer 6

Yellow and green

Question 7

What does a fuse do?

Answer 7

Prevents fires, is very cheap at 20p, a thin wire that melts when current exceeds its rating, 3A,5A,13A

Question 8

Why do some devices not have an earth wire?

Answer 8

Can be connected to same material that live wire is touching to prevent electrocution, an appliance can also be double insulated with the live wire only touching the inner casing of that appliance

Question 9

What is power?

Answer 9

Work done

Question 10

What do electrons have to get past in a current?

Answer 10

They have to get past ions without colliding to prevent resistance and kinetic and thermal energy will be released meaning higher resistance

Question 11

What is efficiency

Answer 11

Useful output over total input X100

Question 12

What is frequency of electricity?

Answer 12

50Hz

Question 13

What is a step-up transformer used for?

Answer 13

To raise voltage but keep current low to reduce resistance leading to heat loss