Brainscape's Knowledge GenomeTM

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


See full index

A Level Summer - Physics > Electricity (E) > Flashcards

Electricity (E) Flashcards

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

Current:

A

The rate of flow of positive charge carriers

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

What is current measured in?

A

Amps

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

equation relating time, charge and current

A

charge = current x time (Q=It)

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

What is conventional flow:

A

flow of charge from positive to negative

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

What is electron flow?

A

Negatively charged electrons flow from negative terminal of cell to positive.

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

What measures current?

A

An ammeter in series

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

What is potential difference?

A

the work done per unit charge in volts

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

Equation relating potential difference and work done:

A

potential difference = work done/charge

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

Resistance:

A

the opposition to current

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

The higher the resistance…

A

the lower the current

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

Why are wires often made of copper?

A

As they have very low resistance so are very good electrical conductors

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

equation for resistance, potential difference and current

A

resistance = potential difference / current

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

what is an ohm?

A

one volt per amp

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

State Ohm’s law:

A

For a conductor at a constant temperature, the current through it is proportional to the potential difference across it.

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

How can you investigate Ohm’s law?

A

adjusting a variable resistor to vary the current in the circuit. Measure voltage across fixed resistor as current varies. Draw graph.

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

How can you tell form a graph if a component obeys Ohm’s law?

A

straight line through the origin

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

Draw diode current voltage graph:

A

straight line on x axes until a little after origin on x axes it goes steeply upwards

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

Draw filament lamp current voltage graph:

A

initially follows ohmic component trend but as voltage gets too high, current flattens

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

Resistivity describes:

A

The extent to which a material opposes the flow of electric current through it

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

What happens as free electrons move through metal wire?

A

they collide with ions, transferring their energy upon collision

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

what is resistivity measured in?

A

ohm metres

22
Q

higher resistivity=

A

higher resistance

23
Q

What does higher temp do to resistance and why?

A

Higher temp means ions inside wire vibrate faster so there are more collisions, slowing them down so current decreases

24
Q

What does a thermistor do?

A

As the temperature increases, the resistance decreases.

25
Q

Draw symbol for thermistor:

A

—box with hockey stick through it—–

26
Q

What is superconductivity?

A

If a material is below a temperature called the critical temperature, its resistivity disappears entirely. it is now a superconductor

27
Q

What are superconductors useful for?

A

applications that require a large electric field or reductions of energy loss

28
Q

name 4 uses of superconductors:

A

MRI scanners, transformers, motors, electromagnets

29
Q

What does a light dependant resistor do?

A

As the light intensity increases the resistance decreases.

30
Q

Resistors in series:

A

combined resistance of components = sum of all individual resistances (Rt = R1 + R2 + R3…)

31
Q

Resistors in parallel:

A

reciprocal of combined resistance = reciprocal of individual resistances (1/R = 1/R1+ 1/R2 …)

32
Q

Current in series:

A

current is same for all components

33
Q

Current in parallel:

A

current is split across branches. total current in junction = total current out of a junction

34
Q

Potential difference in series:

A

emd is shared amongst all components depending on their resistance

35
Q

Potential difference in parallel:

A

voltage of all components in each branch = emf

36
Q

Charge is never…

A

used up or lost

37
Q

What is KIRCHHOFF’s first law?

A

sum of currents entering a junction = sum of currents coming out of a junction (I = I1 + I2 +….)

38
Q

junction:

A

point where at least three circuit paths meet

39
Q

branch:

A

point connecting two junctions

40
Q

Energy is never…

A

used up or lost

41
Q

What is KIRCHHOFF’s second law?

A

the total emf in a closed circuit equals the sum of the potential difference across each component (each closed circuit can be treated like a series circuit)

42
Q

The sum of emfs in each closed loop =

A

emf of power supply

43
Q

What is electrical power?

A

rate of change of work done

44
Q

Power equation (wd and time) :

A

work done / time

45
Q

What is work done?

A

Energy transferred

46
Q

Power equation (current and voltage)=

A

current x voltage

47
Q

Using Ohm’s law, how can you rewrite the power equation?

A

P=I^2R or P=V^2/R

48
Q

How can you calculate energy transferred?

A

voltage x current x time

49
Q

When two resistors are connected in series…

A

through K’s second law, the p.d across the power source divides between the two

50
Q

Potential dividers:

A

circuits which produce an output voltage as a fraction of its input voltage

51
Q

What are the three main purposes of potential dividers?

A

to provide variable potential differences, to enable specific pd to be chosen, to split pd of a power source between two or more componenets

52
Q

V out =

A

(R2/R1+R2) x V in

A Level Summer - Physics (6 decks)

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