Brainscape's Knowledge GenomeTM

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


See full index

PHYSICS > ELECTRICITY > Flashcards

ELECTRICITY Flashcards

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

What is current?

A

The flow of electrical charge (amps)
Rate of flow of electrons

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

What is potential difference?

A

The driving force that pushes the charge around from battery (volts)

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

What is resistance?

A

Anything that slows the flow down (ohms)

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

What does the flow of the current depend on?

A

The greater the resistance the smaller the current (for a given potential difference)

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

What is the relationship between current and potential difference?

A

They are directly proportional (resistance is constant)

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

What are the only resistors in which the resistance can change?

A

A diode
A filament lamp

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

What is charge?

A

The flow of eletrons

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

What is the current like through an ohmic conductor (e.g. resistor)?

A

The current is directly proportional to the potential difference

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

What is the current like through a filament lamp?

A

As the current increases, the temp increases so the resistance increases (curves)

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

What is the current like through a diode?

A

Current can only flow through a diode in one direction

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

What is the current in a series circuit?

A

Same

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

What is the potential difference in a series circuit?

A

Adds

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

What is the current in a parallel circuit?

A

Adds

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

What is the potential difference in a parallel circuit?

A

Same

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

What is the resistance in a series circuit?

A

Adds

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

What happens do the resistance in a parallel circuit?

A

The total resistance reduces
Current increases as more paths to go through which means decrease in total resistance because V = IR

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

What is an LDR (light dependant resistor)?

A

A resistor that is dependant on light intensity
When light increases resistance decreases (light off)
When light decreases resistance increases (light on)

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

What is a thermistor?

A

A temperature dependant resistor
When temp increases resistance decreases (off)
When temp decreases resistance increases (on)

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

Why do LDR’s and thermistors turn on when the resistance is increased?

A

Because more force is needed to push through the resister so voltage/potential difference increases

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

What happens to the current if you decrease the reistance?

A

The current increases

21
Q

What will happen in a circuit with an LDR if light intensity is high?

A

Resistance decreases so current increases so the reading on an ammeter will increase

22
Q

What is an alternating current (ac) electrical supply?

A

When the current is constantly changing direction created by alternating voltages
(e.g. uk mains supply at around 230V)

23
Q

What is a direct current (dc) electrical supply?

A

When the current flows in the same direction all the time and is created by a direct voltage
(e.g. battery and cells)

24
Q

What is a three-core cable?

A

Three wires with a core of copper and coloured plastic coating

25
Q

What colour is the neutral wire?

A

Blue

26
Q

What colour is the live wire?

A

Brown

27
Q

What colour is the earth wire?

A

Green and yellow

28
Q

What does the earth wire do?

A

Protects wiring and for safety
Stops the appliance casing from becoming live
0V

29
Q

What does the live wire do?

A

This provides the alternating potential difference from the mains supply
230V

30
Q

What does the neutral wire do?

A

Completes the circuit
0V

31
Q

What does the fuse do in a plug?

A

The fuse breaks the circuit if a fault in an appliance causes too much current to flow

32
Q

Where can energy be transferred to in a circuit (current)?

A

A moving charge (current) transfers energy because the charge does work against the resistance
The higher the current the more energy transferred to the thermal energy store

33
Q

What does the power rating on an electrical appliance tell you?

A

The maximum amount of energy transferred between stores per second when the appliance is in use

34
Q

What is the letter for charge flow?

A

Q

35
Q

What happens when an electrical charge goes through a change in potential difference?

A

Energy is transferred

36
Q

What is the national grid?

A

A giant system of cables and transformers that connects power stations to consumers (houses etc.)

37
Q

How does the national grid cope with demand?

A

Usually runs below maximum power output so there is spare capacity to cope with high demand (usually they can predict when this will occur)

38
Q

Why is a high potential difference used to transmit huge amounts of power instead of high current in the national grid?

A

Because a high current means you lose loads of energy as the wires heat up to the thermal energy store

39
Q

How is the national grid efficient?

A

Boosting potential difference is cheap and doesn’t lose energy to thermal energy stores (like a high current would)
Also decreases current which decreases energy lost to thermal energy stores

40
Q

What do step-up and step-down transformers do?

A

Step-up: increases potential difference and decreases current
Step-down: reduces potential difference so it is as a useable level for everyday electrical appliances (e.g. in a household)

41
Q

What does a transformer contain?

A

Two coils (a primary and secondary one) joined with an iron core

42
Q

What is static electricity?

A

Electricity in charges that are not free to move (e.g. insulation materials)

43
Q

What happens when certain insulating materials are rubbed together?

A

Negatively charged electrons will be scarped off and dumped on the other
This will leave the materials electrically charged (one positive and one negative)

44
Q

Why does too much static cause sparks?

A

As electric charge builds, the potential difference between an object and the earth increases (0V)
If the pd gets larger enough then electrons can jump across the gap between the object and the earth (spark)

45
Q

What is electrostatic attraction / repulsion?

A

Opposite electric charges attract
Same electric charges repel
These forces get weaker the further apart the objects are
These forces can cause the objects to move

46
Q

What is an electric field?

A

It is created around any electrically charged object

47
Q

Where do the arrows point on an electric field diagram?

A

Positive = away from centre
Negative = towards centre

48
Q

What happens when two oppositely charged particles move in range of each other?

A

Their electric fields interact
Forces act on both particles
These forces move the particles closer together

PHYSICS (12 decks)

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