Brainscape's Knowledge GenomeTM

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


See full index

GCSE AQA Physics > Topic 2 - Electricity > Flashcards

Topic 2 - Electricity Flashcards

1
Q

Define

electrical current.

and give its unit

A

the rate of flow of charge

amps (A)

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

What is

potential difference?

(or voltage) and give its unit

A

the drivinf force that pushes the charge round

volts (V)

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

What is

resistance?

and give its unit

A

anything that slows the flow down

ohms (Ω)

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

What equation links current, charge flow and time?

A

charge flow = current x time

Q = It

Q: coulombs, C
I: amps, A
t: seconds, s

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

How would you draw a

fuse

for a circuit diagram?

A

a rectangle with the wire running through it

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

How would you draw a

variable resistor

for a circuit diagram?

A

a rectangle with a diagonal arrow going through it

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

How would you draw a

thermistor

for a circuit diagram?

A

a rectangle with a straight then diagonal line going through it

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

How would you a draw an

LED

for a circuit diagram?

A

a diode with two arrows pointing north east out of it

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

How would you drawn an

LDR

for a circuit diagram?

A

a small resistor with a circle around it with two arrows pointing into it, south east

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

What equation links

current, potential difference and resistance?

A

potential difference = current x resistance

V = IR

V: volts (V)
I: amps (A)
R: ohms (Ω)

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

Explain the I-V graph for an

ohmic conductor.

A

The current through an ohmic conductor (at a constant temperature) is directly proportional to potential difference so you get a straight line.

(looks like a y=x graph)

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

Explain the I-V graph for a

filament lamp.

A

As the current increases, the temperature of the filament increases, so the resistance increases. This means less current can flow per unit pd, so the graph gets shallower - hence the curve.

(looks like the middle bit of a sin graph)

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

Explain the I-V graph for a

diode.

A

Current will only flow through a diode in one direction, as shown. The diode has a very high resistance in the reverse direction.

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

What is the relationship between resistance and light intensity in an LDR?

A

resistance is inversely proportional to light intensity

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

What is the relationship between resistance and temperature in a thermistor?

A

resistance is inversely proportional to temperature

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

What is the voltage from the UK mains supply?

and what kind of supply is this?

A

230V

ac

17
Q

What is the frequency of the ac mains supply?

A

50Hz

18
Q

How are most electrical appliances connected to the mains supply?

A

by three-core cables

this means that they have three wires inside them, each with a core of copper and a coloured plastic coating

19
Q

What is the purpose of the

live wire?

and what is its colour?
and pd?

A

the live wire provides the alternating potential difference from the mains supply

brown, about 230V

20
Q

What is the purpose of the

neutral wire?

and what is its colour?
and pd?

A

the neutral wire completes the circuit - when the appliance is operating normally, current flows through the live and neutral wires

blue, around 0V

21
Q

What is the purpose of the

earth wire?

and what is its colour?
and pd?

A

it is for protecting the wiring, and for safety - it stops the appliance casing from becoming live, it doesn’t usually carry a current - only when there’s a fault

green and yellow, 0V

22
Q

What would happen if you touched a

live wire?

and why?

A

a large electric shock would be caused, which could injure you or even kill you

Your body is at 0V. If you touch the live wire, a large potential difference is produced across your body and a current flows through you.

23
Q

What is the power of an appliance?

A

the energy that it transfers per second

24
Q

What equation links

charge flow, energy transferred and potential difference?

A

energy transferred = potential difference x charge flow

E = VQ

E: joules, J
V: volts, V
Q: coulombs, C

25
Q

What equation links

power, potential difference and current?

A

power = current x potential difference

P = IV

P: watts, W
I: amps, A
V: volts, V

26
Q

What equation links

current, resistance and power?

A

power = current x current x resistance

P = IIR

P: watts, W
I: amps, A
R: ohms, Ω

27
Q

What is the

national grid?

and what does it do?

A

a giant system of cables and transformers that covers the UK and connects power stations to consumers

it transfers electrical power from power stations anywhere on the grid to anywhere else on the grid where it’s needed

28
Q

What equation explores current and potential difference in the coils of a transformer?

A

Vs x Is = Vp x Ip

29
Q

What equation links

voltage and number of turns of wire

in a transformer?

A

Vp / Vs = Np / Ns

30
Q

How do transformers make the national grid an efficient way of transferring energy?

A

for a given power, increasing the pd decreases the current, which decreases the energy lost by heating the wires and the surroundings

31
Q

What is

static electricity?

A

charges which are not free to move

32
Q

How are

sparks created?

(2 steps)

A
  1. As electric charge builds up on an object, the potential difference between the object and the earth (which is at 0V) increases.
  2. If the potential difference gets large enough, electrons can jump across the gap between the charged object and the earth.

(this usually happens when the gap is fairly small)

33
Q

What are some rules about

electric field lines?

(3 rules)

A
  • they go from positive to negative
  • they’re always at a right angle to the surface
  • the closer together the lines are, the stronger the field is
34
Q

How do

electric fields explain sparks?

(4 steps)

A
  1. Sparks are caused when there is a high enough potential difference between a charged object and the earth.
  2. A high potential difference causes a strong electric field between the charged object and the earthed object.
  3. The strong electric field causes electrons in the air particles to be removed (known as ionisation).
  4. Air is normally an insulator, but when it is ionised it is much more conductive, so a current can flow through it.

GCSE AQA Physics (8 decks)

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