P2

Question 1

define current

Answer 1

the flow of electrical charge

Question 2

give an equation that links current, charge and time, with units for each

Answer 2

charge flow(coulombs, C)= current(amps, A) * time(seconds, S)

Question 3

what is the equation that links potential difference current and resistance

Answer 3

potential difference (v)= current (A) * resistance (ohms)

Question 4

what is an ohmic conductor

Answer 4

a conductor which follows ohms law

Question 5

what happens to the resistance of a thermistor as it gets hot

Answer 5

the resistance drops

Question 6

is potential difference shared between components in a series circuit

Answer 6

yes

Question 7

how does the current through each component vary in a series circuit

Answer 7

there will be less current flowing through them the more components you have

Question 8

is current shared between the branches of a parallel circuit

Answer 8

yes

Question 9

is mains electricity alternating current

Answer 9

yes

Question 10

what is the potential difference and the frequency of the UK mains supply

Answer 10

frequency is 50 HZ

PD is 230 V

Question 11

what colour is the earth wire

Answer 11

green and yellow

Question 12

what wire is blue

Answer 12

neutral

Question 13

what wire is brown and dangerous to touch

Answer 13

live

Question 14

why is the live wire dangerous

Answer 14

it has about 230 v in it

Question 15

describe the energy transfers that occur for a battery-powered fan

Answer 15

electrical energy

Question 16

what is the power rating of an appliance

Answer 16

it tells you how much power the appliance uses, given in watts or kilowatts

Question 17

3 equations used to calculate power

Answer 17

potential difference * current = power
power = energy transferred/time
power=current squared * resistance

Question 18

what is the national grid

Answer 18

a giant web of wires that covers the whole of Britain spreading the electricity to homes

Question 19

why is electricity transferred by the national grid at a high PD but low current

Answer 19

so it is more efficient

Question 20

what are the functions of step up and step down transformers

Answer 20

they increase and decrease the potential difference