Electricity Physics

Question 1

What’s current measured in

Answer 1

Amperes (A)

Question 2

Definition of current

Answer 2

A measure of the flow of electrons around a circuit

Question 3

What’s potential different measured in

Answer 3

Voltage (V)

Question 4

Definition of potential difference

Answer 4

Force driving flow of electrons around

Question 5

What’s resistance measured in

Answer 5

Ohms

Question 6

Definition of resistance

Answer 6

Everything that opposes flow of electrons around

Question 7

Is the longer line on a battery positive or negative

Answer 7

Positive

Question 8

In what direction does current flow in

Answer 8

Positive to negative (long to short)

Question 9

Are ammeters added in series or parallel

Answer 9

Series

Question 10

Are voltmeters added in series or parallel

Answer 10

Parallel

Question 11

Use of a fixed resistor

Answer 11

Prove certain number of ohms of resistance

Question 12

What does a variable resistor do

Answer 12

Modify amount of resistance

Question 13

What does LDR resistance depend on

Answer 13

Intensity of light

Question 14

Uses of LDR

Answer 14

Automatic night lights
Burglar alarms

Question 15

What’s a thermistor resistance dependent on

Answer 15

Temperature

Question 16

Uses of thermistors

Answer 16

Temperature receptors in car engines and electronic thermostats

Question 17

What happens to the resistance in an LDR in bright light

Answer 17

Low resistance so lots of current can flow

Question 18

Higher temperatures in a thermistor does what to resistance

Answer 18

Decreases resistance

Question 19

In series circuit what’s the rule of potential difference

Answer 19

Its shared

Question 20

In series what’s the rule of current

Answer 20

It’s the same everywhere

Question 21

In series what’s the rule of resistance

Answer 21

The total resistance is equal to all individual resistances of each components

Question 22

In parallel what’s the rule of potential difference

Answer 22

It’s the same everywhere

Question 23

In parallel what’s the rule of current

Answer 23

Shared between all loops and adds to total current

Question 24

What’s the resistance rule in parallel

Answer 24

The more components the lower the total resistance

Question 25

How do power stations work

Answer 25

They generate loads of heat and convert the thermal energy into electrical energy

Question 26

When does electricity demand peak

Answer 26

Late afternoon and evening

Question 27

How do power stations cope with demands for electricity

Answer 27

They run well below maximum power output

Question 28

What do step up transformers do

Answer 28

Increase voltage to 400,000 V

Question 29

What do step down transformers do

Answer 29

Reduce voltage to 230V

Question 30

Why are step up and step down transformers necessary

Answer 30

Because there must be a really high voltage and low current when electricity travels through pylons to reduce lose of energy through the heating of wires

Question 31

What does AC stand for

Answer 31

Alternating current

Question 32

What does DC stand for

Answer 32

Direct current

Question 33

Is mains supply ac or dc

Answer 33

Ac

Question 34

What’s mains supply Hz and V

Answer 34

50 Hz and 230V

Question 35

When is ac produced

Answer 35

When we use an alternating potential difference

Question 36

What colour is the live wire

Answer 36

Brown

Question 37

Use of live wire

Answer 37

Provides alternating potential difference

Question 38

Colour of neutral wire

Answer 38

Blue

Question 39

Use of neutral wire

Answer 39

Completes circuit by carrying away current

Question 40

Colour of earth wire

Answer 40

Green and yellow

Question 41

Use of earth wire

Answer 41

Stop appliance casing becoming live by providing an alternative pathway for current to flow in

Question 42

Why causes an electric shock

Answer 42

there is a difference in voltage causing electricity to pass from the live wire to us

Question 44

What’s a surge

Answer 44

A sudden increase in current

Question 45

What can surges cause

Answer 45

Damage to appliances, cause fires, electric shock

Question 46

What do fuses do

Answer 46

Break the circuit whenever current gets too high

Question 47

Why are circuit breakers better than fuses

Answer 47

Fuses are only single use

Question 48

Why are fuses better than circuit breakers

Answer 48

Fuses are cheaper

Question 49

What do circuit breakers do

Answer 49

Turn off the circuit whenever current is too high

Question 50

In conducting materials why does no charge ever build up

Answer 50

Electrons flow straight back

Question 51

What happens to the charges of insulating materials

Answer 51

Electrons can’t flow back so a positive static charge is left on the material that lost electrons and a negative on the one that gained electrons

Question 52

What direction to field lines go in

Answer 52

Positive to negative (must be at right angles to the surface)