Brainscape's Knowledge GenomeTM

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


See full index

GCSE Physics > Electricity > Flashcards

Electricity Flashcards

You may prefer our related Brainscape-certified flashcards:
Physics 101 flashcards GCSE Religious Studies - Edexcel Route A flashcards AP® Physics flashcards GCSE Religious Studies - Eduqas Route A flashcards GCSE Geography - AQA flashcards GCSE Religious Studies - Edexcel Route B flashcards GCSE Religious Studies - Eduqas Route B flashcards
1
Q

What is an electric current?

A

A flow of electric charge.

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

What is the equation linking charge, current and time?

A

charge = current x time

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

What can be said about the value of current at any point in a single closed loop?

A

Current is the same at all points in a closed loop.

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

What two factors does the current in a circuit depend on?

A
  1. Potential Difference (V)
  2. Resistance (R)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What equation should be used to calculate potential difference if current and resistance are known?

A

V = I R
Potential Difference (V), = Current (A) x Resistance (Ω)

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

What is an ‘Ohmic Conductor’?

A

● A conductor for which current and potential difference are directly proportional
● Resistance remains constant as current changes
● Temperature must be constant

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

List four components for which resistance is not constant as current changes.

A
  1. Lamps
  2. Diodes
  3. Thermistors
  4. Light Dependant Resistors (LDRs)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What happens to the resistance of a filament lamps as the temperature increases? Why?

A

Resistance increases
Ions in metal have more energy, so vibrate more, causing more collisions with electrons as they flow through the metal, creating greater resistance to current flow

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

What is different about current flow through a diode?

A
  • The current only flows in one direction
  • Resistance is very high in the other direction, preventing current flow
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

what happens to the resistance of a thermistor as temperature increases?

A

The thermistor’s resistance decreases.

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

Give two examples of when a thermistor may be used

A
  1. In a thermostat to turn a heater on below a certain temperature
  2. In a freezer to turn on a cooler when the temperature becomes too high
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

State what happens to the resistance of a LDR as light intensity decreases.

A

The LDR’s resistance increases.

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

Give an application for a LDR.

A

● Street lights often use LDRs
● When light levels become too low, the
light gains sufficient current to turn on

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

What are the two ways that a component can be connected in a circuit?

A
  1. Series (same loop)
  2. Parallel (adjacent loop)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does the potential difference across two components vary when connected in series and parallel?

A

● Series: Total P.D is shared between each component
● Parallel: P.D across each component is the same

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

If two resistors are connected in parallel, what can be said about their combined total resistance?

A

Their total resistance is less than the smallest of the two individual resistances.

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

If two resistors are connected in series, what can be said about their total resistance?

A

Their total combined resistance is equal to the sum of the two individual resistances.

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

Describe the current in a series circuit

A

In a series circuit, the current is the same at all positions since the charge only has one path to flow through.

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

Describe the current in a parallel circuit

A

In a parallel circuit, the current is shared between the different branches. When the charge reaches a junction it splits.

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

How should you connect an ammeter in a circuit to measure current?

A

Ammeters should be connected in series with the component that they are measuring current through.

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

How should you connect a voltmeter in a circuit to measure potential difference?

A

Voltmeters should be connected in parallel to the component that they are measuring the potential difference of.

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

Why is it advantageous to connect lamps in parallel?

A

If one lamp blows, the rest will be unaffected and can still receive current (i.e. the circuit is still complete).

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

Is mains electricity an a.c supply or a d.c supply? What do each of these stand for?

A

Mains electricity is an a.c supply
a.c. : Alternating Current
d.c. : Direct Current

24
Q

Define alternating current and direct current

A

● Alternating current: Current that continuously changes direction at a specific frequency
● Direct current: One directional current flow

25
Q

What is the frequency and voltage of the UK mains electricity supply?

A

● Frequency: 50 Hz
● Voltage: 230V

26
Q

How many wires are usually in the cables connecting electrical appliances to the mains? Name these wires.

A
  1. Live wire
  2. Neutral wire
  3. Earth wire
27
Q

State the insulation colour used on the Earth wire.

A

Green and yellow stripes

28
Q

State the insulation colour used on the live wire.

A

brown

29
Q

State the insulation colour used on the neutral wire.

A

Blue

30
Q

Explain when the Earth wire does and doesn’t carry a current.

A

● Under normal circumstances, no current flows through the Earth wire
● If a fault occurs in the appliance (such as a surge or the casing becoming live), current will flow to the ground

31
Q

What potential is the neutral wire at?

A

0 volts

32
Q

State the potential difference between the live and earth wires.

A

230 volts

33
Q

What is the purpose of the neutral wire?

A

To complete the circuit by connecting the appliance back to the mains supply.

34
Q

For metal appliances, where is the Earth wire connected to? Why?

A

● Earth wire is connected to the metal casing of the appliance
● If live wire becomes loose and touches the casing, the current will flow through the Earth wire, preventing electrocution

35
Q

State two equations for the power of a circuit. Give appropriate units.

A

P = I V P = I² R
Power (Watts), Current (Amperes) Potential Difference (Volts), Resistance (Ohms)

36
Q

State an equation linking energy transferred, power and time. Give appropriate units.

A

E = P t
Energy (Joules), Power (Watts), Time (Seconds)

37
Q

State an equation linking energy transferred, change flow and potential difference. Give appropriate units.

A

E = QV
Energy (joules), charge (coulombs), potential difference (volts)

38
Q

What two main factors does the amount of energy transferred by an appliance depend on?

A

How long the appliance is being used for
- The power of the appliance

39
Q

Describe the energy transfers in a battery powered torch

A

● Battery converts chemical energy into electrical energy
● Bulb converts electrical energy into light as well as waste energy in the form of heating

40
Q

Describe the energy transfers in a battery powered motor

A

● Battery converts chemical energy into electrical energy
● Motor converts electrical energy into kinetic energy as well as waste energy in the form of heating due to friction

41
Q

What three things determine the power of a circuit device?

A
  • the potential difference across the circuit
  • the current through the circuit
  • the amount of energy transferred in a given time
42
Q

What is the purpose of the national grid?

A

To link power stations to consumers so that they have access to a source of electricity.

43
Q

What are the two types of transformers used in the national grid?

A

Step-up transformers and step-down transformers

44
Q

Where are step-up transformers found in the National Grid? What do they do?

A

Where are step-up transformers found in the National Grid? What do they do?

45
Q

Where are step-down transformers found in the National Grid? What do they do?

A

● Step-Down Transformers are used in connecting transmission cables to domestic buildings (like houses)
● They decrease the potential difference

46
Q

Why do transmission lines transfer electricity at high potentials?

A

● A high potential, results in a low current
● The lower the current, the less energy that is wasted as heat
● Therefore it is more efficient

47
Q

Why does the potential need to be decreased between transmission lines and houses?

A

● Lower potentials are safer for domestic use and reduces the likelihood of
severe electrocution
● Appliances are designed for 230V

48
Q

What can happen when insulating materials are rubbed together?

A

They can become (statically) electrically charged.

49
Q

What happens when two electrically charged objects are bought close together?

A

They exert a force on each other

50
Q

What happens when two identically charged objects are brought close together?

A

They exert a repulsive force on each other and repel.

51
Q

What happens when two oppositely charged objects are bought close together?

A

They exert an attractive force on each other and attract

52
Q

Give an example of non-contact force

A

The repulsive or attractive force acting between two electrically charged objects.

53
Q

What is an electric field?

A

a region around a charged particle or object within which a force would be exerted on other charged particles or objects.

54
Q

Where can electric fields be found?

A

Surrounding any charged object.

55
Q

Describe the electric field around a charged particle?

A

● Strongest closest to the object
● Decreases in strength as you move away from the object

56
Q

What happens to the force between two charged objects when they are moved closer together?

A

The force between them becomes stronger as the separation reduces.

57
Q

In situations where sparks are unwanted, what precaution must be taken to prevent the build up of static charge?

A

Any surfaces that are rubbing against each other should be earthed to allow the charge to flow off the materials.

GCSE Physics (8 decks)

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