Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

physics spec > p2 electricity > Flashcards

p2 electricity Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards AP® Physics flashcards
1
Q

what must an electrical current in a closed circuit need to flow?

A

a source of potential difference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
1
Q

what must an electrical current in a closed circuit need to flow?

A

a source of potential difference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is a current?

A

the flow of charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what is the equation linking charge flow, current and time?

A

charge flow= current x time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

rule of the current in a series circuit?

A

the current is the same everywhere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the current in a circuit determined by?

A

resistance and potential difference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

whats the relationship between current and resistance?

A

the higher the resistance of a component , the lower the current for a given potential difference across the component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

what is the equation linking pd, current and resistance?

A

pd= current x resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what is the difference between a variable resistor and a control resistor?

A

variable resistor’s resistance is determined due to factors such as light or heat, whereas control resistors have the same resistance regardless of external factors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

is the resistance of ohmic conductors constant?

A

yes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what is the relationship between potential difference and current in an ohmic conductor at constant temp?

A

they are directly proportional

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

examples of components with variable resistance?

A

diode, thermistor, filament lamp and light depended resistors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

what is the resistance determined by in a filament lamp?

A

temperature. the resistance increases as the temp of the filament increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

what is the resistance determined by in a diode?

A

direction of the flow of current. the resistance is extremely high in the reverse direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what is the resistance determined by in a thermistor?

A

temperature. when the temperature increases, the resistance decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

application of thermistors in appliances?

A

thermostats

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what is the resistance determined by in an LDR?

A

light intensity. when the light intensity increases, the resistance decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

application of LDR?

A

in circuits eg switching on lights when it gets dark

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

series circuit rules?

A

1) there is the same current through each component
2) the total potential difference of the power supply is shared
between the components
3) the total resistance of two components is the sum of the
resistance of each component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

equation for total resistance?

A

TR= resistance of R1 + resistance of R2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

parallel circuit rules?

A

1) the potential difference across each component is the same
2) the total current through the whole circuit is the sum of the
currents through the separate components
3) the total resistance of two resistors is less than the resistance
of the smallest individual resistor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

why is the total resistance of two components in parallel less than the resistor with the least resistance?

A

> in parallel, both resistors have the same PD across them as the source
> this means that the current is flowing the same as the source of PD for each resistor that u add
» by adding another loop, the current has more than one direction to go in
»> this increases the total current that can flow around the circuit, an increase in current means a decrease in the total resistance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what is direct current?

A

current that only flows in one direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what is alternating current?

A

current that constantly changes direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what is an alternating current produced by?

A

alternating potential difference, from positive to negative

25
Q

what is the mains electricity?

A

an AC supply

26
Q

what is the frequency and voltage of the electricity supplied by the mains electricity supply?

A

50 hertz and 230v

27
Q

what colour is the live wire?

A

brown

28
Q

what colour in the earth wire?

A

yellow and green

29
Q

what colour is the neutral wire?

A

blue

30
Q

function of the live wire?

A

carries the 230v PD from supply to the appliance

31
Q

function of the neutral wire?

A

completes the circuit. when the appliance is operating normally, current flows through the live and neutral wire. it is 0v

32
Q

function of the earth wire?

A

is to stop the appliance casing from becoming live. it does not carry current- ply when theres a fault. also 0v

33
Q

why is a live wire danngerous?

A

our body is at 0v. therefore if we touch a live wire, a large potential difference is produced across your body and a current flows through you. this causes an electric shock which could be fatal

34
Q

how is a live wire dangerous even if the circuit is open?

A

there is still a danger of an electric shock because although the current isnt flowing, there is still a pd in the wire. if you touch this wire, your body wold provide a link between the supply and the earth, so a current would flow through you

35
Q

why are connections between the live and earth wire be dangerous?

A

if the link creates a low resistance path to earth, a huge current would flow which could lead to a fire

36
Q

equation which links power, pd and current?

A

power= pd x current

37
Q

equation that links power, current and resistance?

A

power= (current)^2 x resistance

38
Q

what does the energy supplied by an appliance depend on?

A

how long the appliance has been switched on for

39
Q

how is energy transferred in kettles?

A

transfer energy electrically from the mains ac supply to the thermal energy store of the heating element of the kettle

40
Q

how is energy transferred in electric fans?

A

energy is transferred electrically from the battery of a handheld fan to the kinetic energy store of the fans motor

41
Q

what does high current lead to?

A

an increase in waste energy which dissipates to the surroundings

42
Q

what is done when charge flows through a circuit?

A

work done

43
Q

what is the equation linking energy transferred, power, time?

A

energy transferred= power x time

44
Q

what is the equation linking energy transferred, charge flow and potential difference?

A

energy transferred= charge flow x pd

45
Q

how is power related to potential difference and current?

A

power is P=VI

46
Q

what is the national grid?

A

The National Grid is a system of cables and transformers linking
power stations to consumers

47
Q

what is transferred to consumers using the national grid?

A

electricity power

48
Q

structure of the national grid?

A

power station -> step up transformer -> step down transformer -> consumer

49
Q

what do step- up transformers do and why?

A

increase PD and decrease current for efficient transmission (as high current leads to more heat energy dissipating to the surroundings)

50
Q

what do step-down transformers do and why?

A

decrease PD and increase current for the safety of the suppliers

51
Q

what happens when 2 insulating materials rub against each other?

A

become electrically charged. one material loses electrons while the other gains them. becoming positively or negatively charged

52
Q

what happens when 2 electrically charged objects are bought together?

A

they exert either an attraction or repelling force. these forces are non contact

53
Q

describe the production of static electricity

A

1) 2 insulating materials rub together, electrons will be scraped off and dumped on the other
2) leaving the materials electrically charged. one negative and one positive

54
Q

evidence of attraction?

A

the two objects pull TOWARDS one another

55
Q

evidence of repulsion?

A

two objects push AWAY from one another

56
Q

how is a spark causes?

A

1) as electrical charge builds on an object, the pd between the object and earth (which is at 0V) increases
2) the pd gets large enough that electrons can jump across the gap between the charged object and earth, this is the spark
3) they can also jump to any earthed conductor that is nearby

57
Q

what do charged objects do?

A

create electrical fields around themselves

58
Q

what is the strength of the electric field dependent on?

A

its distance from the charged object. the closer it is, the stronger the field is. the further away it is, the weaker it is.

59
Q

what happens when a second charge objects enters the electric field.

A

it experiences a non contact force

physics spec (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions