Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Physics > Electricity > Flashcards

Electricity Flashcards

1
Q

what is needed for charge to flow

A

circuit must be closed
must be a source of potential difference (battery/cell)

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

what is 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 current like in a single , closed loop

A

same value at any point

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

what does the current in a component depend on

A

resistance of the component and potential difference across the component

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

what happens when there is a greater resistance in a component

A

smaller the current for a given potential difference

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

what is ohms law

A

the current passing through a component is directly proportional to the potential difference across it ,provided the temperature is constant

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

what happens to the graph is the resistance of the components is not constant and changes with the current in the component

A

non linear

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

how does resistance change with current

A

as current increases electrons have more energy
when electrons flow through a resistor they collide with atoms in the resistor
this transfers energy to the atoms causing them to vibrate more
this makes it harder for electrons t flow through the resistor
resistance increases and current decreases

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

how does resistance change with temperature in normal wires

A

as temperature increases atoms have more energy
when atoms flow through the resistor they collide with others
transferring mor energy and making them vibrate more
so it is difficult for flow through a resistor
resistance increases

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

how does temperature effect resistance in a thermistor

A

in hotter temperatures resistance is lower
often used in temperature detectors/thermostats

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

how does length affect resistance

A

greater the length the more resistance and lower the current
electrons have to make their way through more resistor atoms so harder than using short wire

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

how does light affect resistance (with an LDR)

A

greater the light intensity , lower the resistance
resistance is greatest when dark
used in automatic night lights

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

how does voltage affect resistance (in diodes)

A

diode allows current to flow freely in one direction
in the opposite direction it has a high resistance so no current can flow

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

what is resistance

A

a measure of how much a material tries to stop current

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

how does diameter affect resistance

A

increasing diameter decreases resistance

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

how does conductivity affect resistance

A

increasing conductivity decreases resistance

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

what are series circuits

A

closed circuit
current follows a single path
current is the same everywhere
total resistance = r1 + r2

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

what is a parallel circuit

A

branched circuits
current splits into multiple paths
total current into a junction= total current in each of the branches
the potential difference is the same across each branch

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

what is the total resistance for two resistors like in parallel

A

less than the resistance of the smaller resistor

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

how are the components connected in series circuits

A

end to end

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

how are components connected in parallel circuits

A

separately to the power supply

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

how does the current flow through components in series

A

all the current flows through all the components

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

how does current flow through parallel

A

flows through each component seperately

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

how is potential difference shared across a series circuit

A

shared across whole circuit
pd of power supply=sum of pd across each component

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
how is current shared through series
same through all parts of the circuit current at one point =current at any other point
26
how is total resistance shared through series
sum of resistance in each component resistance of two components is bigger than just one of them because the charge has to push through both of them when flowing round the circuit
27
how is potential difference shared through parallel circuits
same across all branches pd of power supply=pd of each branch charge can only pass through any one branch
28
how is current shared between parallel
shared between each of the branches current through source = sum of current through each branch
29
what is the resistance across parallel
total is less than the branch with the smallest resistance two resistors in parallel will have a smaller overall resistance than just one charge has more than one branch to take so only some charge will flow along each branch
30
what does an IV graph show
how the current passing through a component changes with potential difference
31
what are the components of an IV graph
fixed resistor filament bulb diode
32
what kind of supply is mains electricity
AC supply
33
what is the frequency of mains electricity in the uk
50hz
34
what is the voltage of mains electricity in the uk
230 V
35
what is ac
alternating current , comes from mains current continuously varies from positive to negative (charge changes direction)
36
what is dc
direct current , movement in one direction only cells and batteries supply direct current
37
what is peak voltage
the maximum height of wave (in a vertical direction) from the zero line measured in volts
38
what is time period of waves
the time for one complete wave to pass, measured in seconds
39
what is frequency
the number of complete waves passing a point per second, measured in hertz
40
what is the frequency equation
1/ time period or f=1/t
41
how do you get an ac supply
needs plugging in from mains , produced by generators
42
what colour is live wire
brown
43
what voltage is live wire
±325V
44
what is the function of a live wire
provides the large alternating pd between it and the neutral wire so an alternating current is produced to power the appliance
45
what colour is a neutral wire
blue
46
what is the voltage of a neutral wire
close to 0V
47
what is the function of a neutral wire
provides a potential difference close to 0V for the live wire to produce a large alternating pd between the two wires
48
what is the colour of an earth wire
yellow/green
49
what is the voltage of an earth wire
0V
50
what is the function of an earth wire
connected to metal cases of an appliance and stops it becoming live if the live wire touches the case. this stops the risk of electric shock to the user
51
how would you get an electric shock from live wires
if it touches the metal casing of the appliance it will become live you get a serious electric shock if you touch it as current flows through you to the ground
52
why is three pin plugs case made of stiff plastic
a poor conductor(insulator) and strong so hard to damage
53
why are wires inside of a plug made if copper
a good conductor and flexible
54
why are pins in a plug made of brass
a good conductor, very strong and doesn't rust
55
why are the wires covered in rubber in plugs
a poor conductor (insulator) and flexible
56
which appliances need an earth wire
only metal appliances there is a risk of electrocution to the user if there is a fault
57
which cables do plastic appliances need
two core cables
58
how are plastic appliances double insulated
the case is made from plastic and copper wires are insulated with rubber
59
what is a fuse
a safety measure to stop appliances overheating and causing a fire. they protect an appliance connected directly to the live wire inside the plug
60
what is power
energy transferred per second. directly proportional to current and voltage
61
what is power loss proportional to
resistance , the square of the current
62
where is energy transferred from and to to be useful energy in devices
transferred from chemical potential in batteries to electrical energy in wires to any form of useful energy in the devices they power
63
which calculation is for electrical power of an appliance
power = current x potential difference or p = i x v
64
what is resistance and its heating effect
when an electric current passes through a conductor, resistance causes the conductor to heat up as the resistor heats up it transfers energy to the surroundings by heating therefore acting as a heater
65
what is the power equation by current and resistance
p = I ˆ2 x R
66
what is the national grid
a system of cables and transformers linking power stations to consumers across the uk
67
how is electricity transferred to uk homes
electricity is generated in a power station and transported around the uk by the national grid
68
what do transformers do
change the voltage and current. transmitting electricity at high voltage reduces power loss , making the system more efficient
69
what is stepping up
increasing the voltage and decreasing the current so a very small current flows through the wires. this reduces heat loss and makes it a more efficient process
70
what is stepping down
decreasing the voltage and increasing the current. our homes and offices operate on a voltage of 230v so the voltage needs to be stepped down to make it safe for use
71
what do step up transformers do
increase. the pd from the power station to the national grid so as the power is constant , current decreases so less energy is lost
72
what do step down transformers do
decrease the pd from the national grid to consumers for consumer safety
73
what is the amount of energy transferred affected by
amount of charge that passes through it each second potential difference across the resistor
74
what is the energy in a circuit equation
energy = charge x potential difference
75
what causes objects to become charged
if friction causes electrons to be transferred
76
what happens when a cloth becomes negatively charged
electrons move from the cloth to the insulator so it becomes negatively charged
77
which particles are free to move in static electricity
electrons
78
what happens if potential difference exists between the two points
negatively charged electrons will move towards the positive side, this is a current flow
79
what happens if two conductors are rubbed
electrons will flow in / out of them cancelling out any effect, so they stay neutral
80
when does sparking occur
when charge builds up, and objects are close but not touching spark is when charge jumps through the air from highly negative object to highly positive object to balance the charges
81
what do the charged objects experience
a force- electrostatic force of attraction or repulsion
82
what are electric fields
fields for charges
83
which direction do electric fields go in
the direction the proton would move = away from positive charges, towards negative charges
84
what happens if a charged object enters an electric field
experiences a force
85
how can objects become charged?
if friction causes electrons to be transferred
86
what happens if a proton moves into a positive electric field
it would repel
87
what happens if an electron moves into a positive electric field
it would attract
88
what happens if there is a potential difference between two points
negatively charged electrons will move towards the positive side (current flow)
89
what is a cell
a source of energy
90
what does an LED do?
emits light when a current is passed through it
91
what does a variable resistor do
allows the current to be varied
92
what is a cell necessary for
push electrons around a complete circuit a battery consists of two or more cells
93
what does a diode do
allows current through in one direction only
94
what does a voltmeter do
measure potential difference
95
what does a switch do
enables the current in a circuit to be switched on or off
96
what does an indicator do
emit light as a signal when a current passes through it or a light source such as a lamp
97
what does a fuse do
melt and therefore break the circuit if the current through it is greater than a certain amount
98
what does a fixed resistor do
limits the current in a circuit
99
what does an ammeter do
measure electric current
100
what is an electrical current
the rate of flow of charge (how much charge flows through a point in the circuit in one second)
101
what is the charge on an electron
1.6 x 10^-19
102
no of electrons
charge / charge of electrons
103
what is potential difference
the work done (energy transferred, J) per coulomb charge that passes between the points
104
what does a bigger potential difference mean
a bigger push for electrons = more current flowing
105
what is potential difference measured in and with
volts, voltmeter
106
what is the voltage equation
work done / charge
107
what is the LDRs resistance affected by
light intensity
108
what is an LDR useful for
where light levels drip below a certain value so a light can be triggered to turn on eg street lights
109
what is the LDR rule
Brightness Increases Resistance Decreases BIRD
110
what is resistance affected by in a thermistor
temperature
111
what are thermistors used in circuits for
to regulate temperatures eg gas ovens, thermostats
112
what is the rule for thermistors
TURD Temperature Up Resistance Down

Physics (19 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions