Topic 2.8-2.11 Electricity in the home

Question 1

What is the formula for electrical power

Answer 1

P=IV
power = current x potential difference

Question 2

When transmitting electricity should the current be high or low and why

Answer 2

low
it generates a lot of wasted heat when high

Question 3

what do step up transformers do

Answer 3

increase potential difference
decrease current

Question 4

what do step down transformers do

Answer 4

decrease potential difference
increase current

Question 5

What is an alternating current

Answer 5

a current that changes direction periodically

Question 6

What is an direct current

Answer 6

a current that flows around the circuit in the same direction

Question 7

what is an alternating current caused by

Answer 7

an alternating potential difference

Question 8

What is direct current supplied by

Answer 8

cells and batteries

Question 9

what is the standard frequency and voltage of the UK mains supply

Answer 9

230V
50Hz

Question 10

What is the role of an oscilloscope

Answer 10

display how the voltage changes with time

Question 11

What colour is the earth wire

Answer 11

green and yellow

Question 12

what colour is the neutral wire

Answer 12

blue

Question 13

what colour is the live wire

Answer 13

brown

Question 14

what colour is the live wire

Answer 14

brown

Question 15

what are the three wires in a plug

Answer 15

earth
live
neutral

Question 16

Which wire prevents the electrical casing from becoming live

Answer 16

Earth

Question 17

Which wire supplies the current to the appliance

Answer 17

live

Question 18

Which wire completes the circuit, allowing current to flow

Answer 18

neutral

Question 19

What is the voltage of the neutral wire

Answer 19

0

Question 20

Explain how fuses work

Answer 20

they are a thin wire that melts if the current is to high