electircity in the home

Question 1

what supply is mains electricty

Answer 1

ac (alternating current)

Question 2

what frequency does the domestic elcetircty supply in the uk have

Answer 2

50Hz

Question 3

what voltage does the domestic electricity supply in the uk have

Answer 3

230V

Question 4

what does dc stand for

Answer 4

direct current

Question 5

what is dc

Answer 5

flows in one direction only

Question 6

what does ac stand for

Answer 6

alternating current

Question 7

what is ac

Answer 7

repeatedly reverses its direction of flow

Question 8

how are most electrical devices connected to the mians

Answer 8

through three-core cable

Question 9

what is the brown wire

Answer 9

the live wire

Question 10

what is the blue wire

Answer 10

the neutral wire

Question 11

what is the green and yellow wire

Answer 11

the earth wire

Question 12

what does the live wire do

Answer 12

carries the alternating potential difference from the supply

Question 13

what does the neutral wire do

Answer 13

completes the circuit

Question 14

what does the earth wire do

Answer 14

saftey wire to stop the appliance becoming live

Question 15

what is the ppotential difference between the live wire and earth wire

Answer 15

230v

Question 16

what voltage does the neautral wire have

Answer 16

0V

Question 17

what voltage does the earth wire have

Answer 17

0V

Question 18

when might the earth wire carry a current

Answer 18

if theres a fault

Question 19

what are the 2 power equations

Answer 19

power = potential difference x current

power = (current)^2 x resistance

Question 20

what is power (P) measured in

Answer 20

watts, W

Question 21

what is potential difference (V) measured in

Answer 21

volts, V

Question 22

what is current (I) measured in

Answer 22

amps, A

Question 23

what is resistance (R) measured in

Answer 23

ohms, Ω

Question 24

what happens when charge flows in a circuit?

Answer 24

work done

Question 25

how to work out energy transferred (both)

Answer 25

energy transferred = power x time

energy transferred = charge flow x potential difference

Question 26

what is energy transferred (E) measured in

Answer 26

joules, J

Question 27

what is charge flow (Q) measured in

Answer 27

coulombs, C

Question 28

what is time (t) measured in

Answer 28

seconds, s

Question 29

how is the power of a circuit device related to the potential difference across it and the current through it, as well as the energy transferred over time?

Answer 29

f either p.d. or current increases, the power increases whcih also increases the rate of energy transfer

Question 30

what is the natioanl grid

Answer 30

system of cables and transformers linking power stations to consumers

Question 31

what are step up transformers used for

Answer 31

to increase the potential difference from the power station to the transmission cables

Question 32

what are step down transformers used for

Answer 32

to decrease, to a much lower value, the potential difference for domestic use.

Question 33

how is electrical power transferred from power stations to consumers

Answer 33

the National Grid

Question 34

why is the national grid system an efficient way to transfer energy

Answer 34

high voltage means low current for the same power, the lower the current means less energy is lost through thermal energy which is produced from current