Applications of electricity

Question 1

function of a resistor

Answer 1

increases resistance of a circuit

Question 2

function of a variable resistor

Answer 2

increases resistance of a circuit and and be changed

Question 3

what is an ohmic conductor

Answer 3

current through an ohmic conductor is directly proportional to the potential difference across the resistor. resistance remains constant as the current changes.

Question 4

what does the current-potential difference graph for an ohmic conductor look like?

Answer 4

a straight line through (0,0)

Question 5

what does the current-potential difference graph for a filament bulb look like

Answer 5

a curved line

Question 6

function of a bulb

Answer 6

produces light radiation

Question 7

what does the current-potential difference graph for a diode look like

Answer 7

a curved line that increases significantly after a certain potential difference

Question 8

function of a diode

Answer 8

allows current to only flow in one direction

Question 9

function of an led

Answer 9

allows current to only flow in one direction, and produces light radiation

Question 10

what happens to the resistance of a thermistor when the temperature changes

Answer 10

resistance decreases as temp increases

Question 11

function of a thermistor

Answer 11

increases resistance of a circuit depending on the temp of the surroundings

Question 12

what happens to the resistance of a LDR when the light intensity changes

Answer 12

resistance decreases as light intensity increases

Question 13

function of an LDR

Answer 13

increases resistance of a circuit depending on the brightness of the surroundings

Question 14

how are thermistors used

Answer 14

in circuits as thermostats

Question 15

how are LDR’s used

Answer 15

in circuits to switch on lights when it gets dark

Question 16

4 examples of non-ohmic conductors

Answer 16

diodes
filament bulbs
LDRs
thermistors

Question 17

what happens to the current through components connected in series?

Answer 17

same current through each component

Question 18

what happens to the total resistance through components connected in series?

Answer 18

total resistance of 2 components=sum of resistance of each component

Question 19

what happens to the potential dif across components connected in series

Answer 19

total potential dif of the power supply is shared between the components

Question 20

what happens to the current through components connected in parallel

Answer 20

current splits across the components

Question 21

what happens to the total resistance of components connected in parallel

Answer 21

total resistance of two resistors is less than the resistance of the small individual resistor

Question 22

what happens to the potential difference across components connected in parallel

Answer 22

the pd across each component is the same

Question 23

what colour is the neutral wire

Answer 23

blue

Question 24

what is the name of the blue wire in a plug

Answer 24

neutral

Question 25

what colour is the earth wire

Answer 25

green and yellow stripes

Question 26

what is the name of the green and yellow striped wire in a plug

Answer 26

earth

Question 27

what colour is the live wire

Answer 27

brown

Question 28

what is the name of the brown wire in a plug

Answer 28

live

Question 29

what is the purpose of the neutral wire

Answer 29

completes the circuit

Question 30

purpose of the live wire?

Answer 30

provides the alternating potential difference

Question 31

purpose of the earth wire?

Answer 31

protects the circuit, stops the appliance casing from becoming live

Question 32

what is the potential difference of a live wire

Answer 32

230V

Question 33

what is the national grid

Answer 33

a system of cables and transformers linking power stations to consumers

Question 34

what is the potential difference of mains electricity

Answer 34

230V

Question 35

what is the frequency of mains electricity

Answer 35

50Hz

Question 36

what type of current is mains electricity

Answer 36

alternating current

Question 37

what is direct current

Answer 37

current flows in one direction around a circuit due to a direct potential difference

Question 38

what is alternating current

Answer 38

current changes direction

Question 39

why does the national grid transmit electricity at very high potential differences

Answer 39

less energy is lost which makes it more efficient

Question 40

what happens at step-up transformers

Answer 40

potential difference increased

Question 41

what happens at step-down transformers

Answer 41

potential difference lowered

Question 42

why do we need step-down transformers

Answer 42

electricity has to be reduced to mains potential difference (230V) to be safe to use in homes.