Y11 Mock Electricity

Question 1

what is needed for electrical charge to flow through a closed circuit

Answer 1

for electrical charge to flow through a closed ciricit the circuit must include a source of potential difference

Question 2

what is electrical current

Answer 2

a flow of electrical charge. the size of the electric current is the rate of flow of electrical charge

Question 3

what does the current through a component depend on

Answer 3

the resistance of the component and the potential difference

Question 4

what is potential difference

Answer 4

the push of electrical charge

Question 5

what is resistance

Answer 5

slows down the flow of electricity

Question 6

resistance practical in series and parallel method

Answer 6

1. construct circuit in series with two resistors, an open switch, a cell, ammeter, voltmeter
2. switch on power supply and close the switch, record voltage and current shown
3. construct new circuit by rearranging the resistors from series to parallel
4. switch on power supply and close the switch. record the voltage and current for this circuit
5. calculate total resistance of each current using v=I X R

Question 7

results of resistance in series circuits from practical

Answer 7

adding resistors in series increases the total resistance of the circuit

Question 8

result of resistance of parallel circuits from practical

Answer 8

the more resistors you add, the smaller the resistance

Question 9

difference in resistors

Answer 9

for some resistors the R value remains constant and for others it doesn’t and can change as the current does

Question 10

what does the ohmic conductor graph show

Answer 10

current is directly proportional to potential difference
straight line through origin

Question 11

describe the filament bulb graph

Answer 11

as current increases so does temperature so it becomes harder for current to flow
graph becomes less steep

Question 12

describe diode graph

Answer 12

current only flows in one direction
resistance is high in the other direction so no current can flow

Question 13

resistance practical in a wire method

Answer 13

1. construct circuit you have drawn
2. set length of wire to 10 cm using croc clip
3. close switch and measure resistance and record
4. open switch and increase length of wire to 20 cm
5. record the new measurement for resistance
6. continue to do this for every 10cm up to 70cm

Question 14

what is the result of resistance in a wire practical

Answer 14

resistance is directly proportional to length

Question 15

what is the current like in series circuits

Answer 15

same current through each component

Question 16

potential difference in series circuits

Answer 16

total pd of power supply is shared between the components

Question 17

resistance in series circuits

Answer 17

resistance will add up to make total resistance

Question 18

current in parallel circuits

Answer 18

total current through the whole circuit it the sum of the currents through the separate components

Question 19

potential difference in parallel

Answer 19

pd across each component is the same

Question 20

voltage of mains electricity

Answer 20

230 v

Question 21

frequency of mains electricity

Answer 21

50 Hz

Question 22

what are everyday appliances designed to do

Answer 22

bring about energy transfers

Question 23

what does amount of energy an appliance transfers depend on

Answer 23

how long the appliance is switched on for, and its power

Question 24

what is AC

Answer 24

alternating current , constantly changing direction 230V and 50Hz

Question 25

what is DC

Answer 25

direct current , supplied by batteries, flows in one direction

Question 26

features of cables

Answer 26

most have 3 wires (live, neutral and earth) , covered in plastic insulation

Question 27

what do cables do

Answer 27

transfer to kinetic energy of electrical motors or energy of heating devices

Question 28

what does the national grid do

Answer 28

transfers electrical power from power stations to consumers

Question 29

what do step up transformers do

Answer 29

increase potential difference from power station to the transmission cables

Question 30

what do step down transformers do

Answer 30

decrease potential difference to a lower value for domestic use

Question 31

how do transformers increase efficiency

Answer 31

step up transformers increase efficiency by increasing voltage which decreases current so reduces heat loss