Brainscape's Knowledge GenomeTM

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


See full index

Physics Daisy > Electricity > Flashcards

Electricity Flashcards

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

Blue wire in a plug

A

Neutral wire - 0 volts

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

Green wire in a plug

A

Earth - 0 volts

Contains an earth wire to provide an alternative path for the current if appliances develop a fault

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

Brown wire in a plug

A

Live - 230 volts

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

What happens if the live wire becomes lose?

A

It touches the metal case, so a very large current will flow to earth and blow the fuse, breaking the circuit

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

What is a fuse?

A

A built in weak point in a circuit - contains a thin wire with a higher resistance than a normal wire

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

What happens if a large current flows through the wire?

A

It becomes too hot so the wire melts and the circuit breaks

Makes a magnetic field produced by the electromagnet, strong enough to open the switch

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

Circuit breakers

A

Does the same job as fuses but they are electromagnetic switches which are easy to reset
Designed to break the circuit if the current gets too high

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

Energy transferred equation

A

Energy = current x potential difference x time

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

The larger the current …

A

The larger the current through a current the more the energy is transferred to it

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

In energy transfers, the higher the current…

A

The more energy transferred to the thermal energy stores of the components
This heating increases the resistance of the components

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

Electrical power

A

Power = energy transferred / time

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

Power

A

The energy that is transferred per second

Measured in watts

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

What does the power transferred by an appliance depend on?

A

Potential difference going across it

Current flowing through it

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

What does the potential difference tell you?

A

How much energy each unit of charge transfers

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

What does the current tell you?

A

How much charge passes per unit time

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

Power supplied equation

A

Power = current x voltage

Can use this equation to work out the fuse that should be used in an appliance

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

Power loss equation

A

P =current 2 x resistance

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

Alternating current

A

The charges are constantly changing direction

They are produced by alternating voltages

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

Direct current

A

The charges always move in the same direction
Created by a direct voltage
Supplied by cells and batteries

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

What is the uk mains supply?

A

Alternating current
50Hz
230 volts

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

What happens electrically if you touch a live wire?

A

A large potential difference is produced across your body and a current flows through you- this causes a large electric shock

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

Why are any connection between live and neutral can be dangerous?

A

If the link created a low resistance path to earth, a huge current will flow - could result in a fire

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

Why do surges in a current occur?

A

Changes in a circuit or because of a fault in an electrical appliance - can lead to wires in the appliance melting

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

Earth wire and fuses - how do they work?

A

Live wire touches metal case- the case in earthed do too great a current flows in through the live wire down the earth wire
Fuse melts- which are connected to the live wire, so that breaking the fuse breaks the circuit and cuts off the live supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Blowing a fuse in a toaster

A

A fault allows the wire to touch the metal
A large current flows out through the earth wire to the earth
This melts the fuse which isolates the appliance and makes it safe

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

LDR

A

Light dependent resistor
In light the resistance falls
In dark the resistance is high
Automatic night lights

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Thermistor

A

A temperature dependent resistor
In heat , resistance drops
In cold, resistance goes up
Temp detectors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Current

A

The flow of electric charge around the circuit

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

When will a current flow?

A

If there is a potential difference across the component and if the circuit is complete - closed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Potential difference

A

The driving force that pushes the charge round

The energy transferred per unit charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Resistance

A

Anything that slows the flow down

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

The higher the potential difference across a given opponent - the

A

Higher the current will be

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

The greater the resistance …

A

The smaller the current that flows

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Equation for total charge

A 
Charge = current x time 
Q= I x T
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Energy transfers from charge and potential difference equation

A

Energy transferred = charge x potential difference

E = Q x V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

The potential difference across an electrical component is …

A

The amount of energy transferred by the electrical component per unit charge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Potential difference , current and resistance equation

A

Potential difference = current x resistance

V=IxR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

When an electrical charge flows through a component,

A

It has to do work against resistance. This causes an electrical transfer of energy - some of this energy is transferred usefully but some is dissipated to the thermal energy stores of the component

39
Q

When current flows through a resistor, the resistor heats up
Why is this?

A

The electrodes collide with the ions in the lattice that make up the resistor as they flow through it
This gives the ions energy which coasters them to vibrate and heat up

40
Q

The more the ions vibrate…

A

The harder it is for electrons to get through the resistor because there are more collisions. - this means that for a given potential difference the current decreases as the resistor heats up

41
Q

What happens if the resistor gets too hot?

A

No current will be able to flow, there is one exception - the resistance of a thermistor decreases with an increase in temp

42
Q

Series circuit

A

The different components are connected in a line, end to end

43
Q

What happens if you remove one component from a series circuit?

A

The circuit is broken and they all stop working

44
Q

Bigger supply - series circuit

A

There is a bigger supply of pd when more cells are in series

45
Q

Current -series

A

The current us the same everywhere

46
Q

Total potential difference - series

A

The total pd of the supply is shared between two components

The pd for each component depends on its resistance

47
Q

Total resistance - series

A

The total resistance of the circuit increases as you add resistors

48
Q

Parallel circuit

A

Each component is separately connected to the positive and negative supply

49
Q

What happens if you remove a component from the parallel circuit?

A

It will hardly affect the others

50
Q

Parallel circuit - pd

A

The potential difference is the same across all components

51
Q

Current in a parallel circuit

A

Shared between branches - the total current flowing around the circuit is equal to the total of all the currents through the separate components

52
Q

Total resistance of a parallel circuit

A

It decreases if you add a second resistor in parallel

53
Q

What happens to the total resistance in a series circuit if you add a resistor?

A

The total resistance of two components is the sum of their resistances - this is because by adding a resistor in series , the two resistors have to share the total pd

54
Q

The potential difference across each resistor …

A

Is lower, so the current through each resistor is also lower

55
Q

In a series circuit, the current is

A

The same everywhere so the total current in the circuit is reduced when a resistor is added - this means the total resistance of the circuit increases

56
Q

The bigger a components resistance is …

A

The bigger it’s share of the total potential difference

57
Q

What happens if you have two resistors in a parallel circuit?

A

The total resistance is less than the resistance of the smallest of the two resistors

58
Q

What happens to the resistance if there are two resistors in a parallel circuit? Explain

A

In parallel, both resistors have the same pd across them. - this means the pushing force making the current flow is the same as the source pd for each resistor
By adding another loop the current can flow in more than 1 direction
This increases the total flow around the circuit

59
Q

Using V=IxR an increase in current…

A

Means a decrease in the total resistance of the circuit

60
Q

Energy in circuits equation

A

E = I x V x T

Energy transferred = current x pd x time

61
Q

When is energy transferred?

A

When an electrical charge goes through a charge in potential difference

62
Q

The larger the current or pd …

A

The more energy is transferred to it

63
Q

voltmeter in circuits

A

is connected in parallel with a component to measure the potential difference in across it, volts

64
Q

Ammeter in circuits

A

is connected in series with a component to measure the current in the component, amps

65
Q

Where is the current conserved?

A

at a junction in the circuit

66
Q

what does the standard circuit test do?

A

investigates the relationship between current, potential difference and resistance for things like a filament light bulb, fixed resistor

67
Q

why do you use a variable resistor in the standard circuit test?

A

it is used to change the current through the circuit. As I=V/R, increasing the total resistance by increasing the variable resistors resistance it decreases the current

68
Q

What does the circuit look like in the standard circuit test?

A

make circuit- component, ammeter, and resistor is in series. voltmeter must be put into parallel

69
Q

Method in standard circuit test

A

change resistance of the variable resistor - measure the current through the pd across the component
take reading from ammeter and voltmeter - calculate means

70
Q

what does the graph look like for the standard circuit test?

A

current against the pd

work out the resistance for each measurement

71
Q

what are the safety precautions in the standard circuit test?

A

make sure it doesn’t get to hot - if it does it will mess up your results

72
Q

LDR - what is it?
Resistance
What are they used for?

A

A resistor that depends on the intensity of light
bright light - resistance falls
dark - resistance at its highest
automatic night lights and burglar detectors

73
Q

thermistor - what is it?
resistance
what are they used for?

A

a temperature dependent resistor
hot - resistance drops
cold - resistance goes up
temp detectors, car engine temp sensor

74
Q

what do iv graphs show?

A

how current varies as you change the pd

75
Q

what does the iv graph look like for resistors and wires?

A 
straight diagonal line going from left to right 
goes through (0,0) - linear graph
76
Q

explain the iv graph for resistor and wires

A

current is directionally proportional to the pd

77
Q

What does the iv graph look like for a filament light bulb?

A

a diagonal s

from left to right

78
Q

explain the iv graph for a filament light bulb

A

the increasing current increases the temp of the bulb which increases the resistance of the bulb

79
Q

what does an iv graph look like for a diode?

A

straight line from top left to curve in top right

80
Q

explain the iv graph for the diode

A

current will only flow through a diode in one direction

the diode has a very high resistance in the other direction

81
Q

method of investigating circuits with adding resistors

A

set out circuit
vary the output pd from the power supply - record the readings
replace the resistor with a filament lamp
then connect a second fl
vary the output pd
write down current and pd

82
Q

what are the results for adding a filament or resistor into a series circuit?

A

as the pd increase, the current through the resistor increases
you should a similar but not linear relationship between pd and current for filament light bulb

83
Q

what are the results for adding a filament or resistor into a parallel circuit?

A

as the pd increases the current increases through each bulb - non linear relationship
total current is the sum of the current though the branches but this is bigger than the current through the series circuit
overall resistance is low

84
Q

when there is an electric current in a resistor there is…

A

an energy transfer which heats the resistor

85
Q

energy transfer in a kettle

A

electrical energy from the mains ac supply to the thermal store of the heating element in the kettle

86
Q

energy transfer in a electrical hand held fan

A

electrical energy transfer from the battery to the kinetic energy store in the fans motor

87
Q

what happens if the current is higher in an energy transfer?

A

the higher the current, the more energy transferred to the thermal energy store of the components and then surroundings

88
Q

what does the increase of heating of an object do to the resistance?

A

increases the resistance of the components

89
Q

what happens during the heating of a wire?

A

As electrons flow through wires, they collide with the ions in the wire which causes the ions to vibrate more. This increased vibration of the ions increases the temperature of the wire.

90
Q

what happens if the circuit gets too hot?

A

can cause components in the circuit to melt which means the circuit will stop and not work properly

91
Q

what do fuses do?

A

they protect circuits by melting and breaking the circuit if the current gets too high

92
Q

advantages of the heating of an electric current - toaster

A

toasters contain a coil of wire with a high resistance

when a current passes through the coil, its temp increases so much it glows and gives off infrared radiation

93
Q

disadvantages of heating an electric current

A

heating up a component generally reduces its efficiency

if the temp gets too high then the circuit melts and breaks

Physics Daisy (11 decks)

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