ELECTRICITY

Question 1

The greater the resistance across a component….

Answer 1

the smaller the current that flows( for a given potential difference across the component

Question 2

CHARGE FLOW =

Answer 2

CURRENT* TIME

Q=IT

Question 3

POTENTIAL DIFFERENCE =

Answer 3

CURRENT * RESISTANCE

V=IR

Question 4

factors that affect resistance

Answer 4

length

if the circuit is in series or parallel

Question 5

what type of resistance do ohmic conductors have

Answer 5

they have a constant resistance

Question 6

Does the resistance of ohmic conductors change with current

Answer 6

No

Question 7

when an ohmic conductor is at a constant temperature

Answer 7

the current flowing through it is directly proportional to the potential difference flowing through it

Question 8

what is an LDR (2 points)

Answer 8

an LDR is an light dependent resistor that is dependent on the intensity of light.

Question 9

what happens to the resistance of an LDR in bright light

Answer 9

the resistance falls

Question 10

what happens to the resistance of an LDR in darkness

Answer 10

the resistance is highest

Question 11

what can you use LDRs for

Answer 11

automatic night lights
outdoor lighting
burgular detectors

Question 12

what is a thermistor

Answer 12

A thermistor is a temperature dependent resistor

Question 13

what happens to the resistance of a thermistor in hot conditions

Answer 13

the resistance drops

Question 14

what happens to the resistance of a thermistor in cool conditions

Answer 14

the resistance goes up

Question 15

where can you use thermistors

Answer 15

they can be useful temperature detectors
car engine temp sensors
electronic thermostats

Question 16

how are the components connected in a series circuit

Answer 16

the components are connected in a line, end to end between the power supply
the voltmeters in a series circuit are always connected in PARALLEL

Question 17

what happens if you disconnect one component in a series circuit

Answer 17

the circuit is broken and they all stop

Question 18

Potential difference is _________________ in a series circuit

Answer 18

the Potential difference is shared between the various components

Question 19

potential difference in a series circuit will always add up to the __________

Answer 19

the source potential difference

Question 20

Equation for potential difference connected in series

Answer 20

Vtotal= V1 + V2 + V3 …..

Question 21

Current in a series circuit is ________

Answer 21

the same through all components

Question 22

Equation for current connected in series

Answer 22

I1=I2=I3=I4

Question 23

In a series circuit the total resistance of two components is the _______ of their resistances

Answer 23

sum

Question 24

when a resistor is added to a series circuit what happens to the current and resistance

Answer 24

the total current is reduced and the resistance is increased

Question 25

in a series circuit cell potential difference (V) ______

Answer 25

adds up

Question 26

How are components connected in a parallel circuit

Answer 26

each component is connected separately to the power supply

Question 27

What happens if you remove components in a parallel circuit

Answer 27

Hardly anything will happen to the cirucit

Question 28

In a Parallel circuit Potential difference is ________

Answer 28

the same across all components

Question 29

will identical bulbs connected in parallel be at the same brightness

Answer 29

yes because potential difference is the same across all components

Question 30

In parallel circuits total current is ______________

Answer 30

is shared across the separate components

Question 31

what does adding a resistor to a parallel circuit do to the resistance and the current

Answer 31

it decreases the resistance and it increases the current

Question 32

What type of current is mains supply

Answer 32

AC current

Question 33

What type of current is battery supply

Answer 33

DC current

Question 34

how are alternating currents produced

Answer 34

they are produced by alternating voltages in which the negative and positive ends keep alternating

Question 35

what voltage is the uk mains supply

Answer 35

230V

Question 36

what is the frequency of the ac mains supply

Answer 36

50 Hz

Question 37

what is dc current and how is it created

Answer 37

Direct current is current that is always flowing in the same direction its created by direct voltage

Question 38

Colour of live wire

Answer 38

brown

Question 39

colour of neutral wire

Answer 39

blue

Question 40

colour of earth wire

Answer 40

green and yellow

Question 41

purpose of the live wire

Answer 41

provides the alternating potential difference at about 230V

Question 42

purpose of neutral wire

Answer 42

the neutral wire completes the circuit and carries away current its around 0V

Question 43

purpose of earth wire

Answer 43

it is for protection, it stops the appliance casing from becoming live its at 0V

Question 44

when do earth wires carry current

Answer 44

when there is a fault

Question 45

why can a live wire give you an electric shock

Answer 45

your body is at 0V this means that if you touch the live wire a large amount of potential difference is produced across your body and current flows through you. This causes an electric shock

Question 46

can you still get an electric shock if the plug socket or switch is turned off

Answer 46

yes because there is still potential difference in the live wire, so if you make contact with the live wire your body would provide a link between the supply and the earth so current will flow through you.

Question 47

equation for power in electrical appliances

Answer 47

ENERGY = POWER * TIME | E=PT

Question 48

What does the power rating tell you

Answer 48

power rating tells you the amount of energy transferred between stores per second

Question 49

the lower the power rating...

Answer 49

the less electricity an appliance uses in a given time so its cheaper to run

Question 50

equation for energy transferred in a circuit

Answer 50

ENERGY= CHARGE FLOW*POTENTIAL DIFFERENCE | E=QV

Question 51

Equation for power in an appliance

Answer 51

power= potential difference * current | p=VI

Question 52

EQUATION FOR POWER WHCIH INVOLES CURRENT AND RESISTANCE

Answer 52

P=I2R

Question 53

What does the national grid use ( pd and Current)

Answer 53

they use a high pd and low current

Question 54

what do step up and step down transformers do

Answer 54

step up transformers increase the potential difference | step down transformers reduce the potential difference for domestic use

Question 55

why is the national grid efficient at transferring energy

Answer 55

the national grid distributes electricity at a high pd and low current. a high pd means that it can distribute lots of power per second. using a low current reduces energy losses which makes the national grid efficient at transferring energy

Question 56

Jake removes his jumper in a dark room he hears a crackling noise and sees tiny sparks between his jumper and his shirt explain

Answer 56

as the jumper rubs against the shirt a static charge builds up between the jumper and the shirt this is due to the electrons being removed from one and being deposited onto the other. The charge becomes large enough for electrons to jump across the small air gap between the jumper and the shirt causing sparks

Question 57

what direction are the field lines on a positively charged isolated sphere

Answer 57

outwards

Question 58

what direction are the field lines on a negatively charged isolated sphere

Answer 58

inwards