P5 electricity in the home

Question 1

AC and DC

Answer 1

DC flows in one direction only

AC repeatedly reverses direction of flow

Question 2

frequency of ac supply

Answer 2

1 / time taken for one cycle

Question 3

wires

Answer 3

live- potential repeatedly changes from + to - and back every cycle
brown
neutral- blue
earth wire- striped yellow and green used to earth metal case of mains appliance

Question 4

step up transformers

Answer 4

at pwr stations to transfer electricity to national grid
increase size of alternating PD
less current needed to transfer same amount of power

Question 5

step down transformers

Answer 5

electricity from national grid to homes

same pwr as 230V DC supply

Question 6

fuse

Answer 6

between live pin and live wire

melts and cuts off live wire if too much current passes through

Question 7

power

Answer 7

current ^2 x resistance

energy transferred to a device each second

Question 8

energy

Answer 8

power x time

Question 9

charge flow

Answer 9

current x time

Q= IT

Question 10

charge flow in a given time

Answer 10

energy supplied by the battery equal to energy transferred to all components in circuit

Question 11

useful energy used

Answer 11

efficiency x energy supplied