Brainscape's Knowledge GenomeTM

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


See full index

Physics A-level > 4.1 Electricuty > Flashcards

4.1 Electricuty Flashcards

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

Electric current is the rate of flow of charge what is the equation for that

A

I = change in charge ( Q ) / Change in time (T)

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

What is conventional current

A

Current flows from positive to negative terminal

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

What is electron flow

A

In reality electrons flow from negative to positive terminal

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

What is kirchoff’s first law

A

The sum of current in and out of a junction algebraically are the same

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

What is electric current and what is the equation

A

The rate of flow of charge
Current= change in charge/ change in time

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

What does e.m.f stand for and what is is

A

electromotive force.
It is the chemical energy to electrical energy per unit charge

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

What does p.d stand for and what is it’s definition

A

Potential difference and it is the electrical energy to other forms of energy

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

How to calculate the e.m.f

A

E.m.f = energy transferred/ charge

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

NEVER BACK DOWN NEVER WHAT???

A

NEVER GIVE UPヾ(⌐■_■)ノ♪

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

Draw the I-V graph for a lamp

A

[draw it]

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

Draw the I-V graph for a diode

A

[draw it]

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

What is resistivity

A

And objects opposition to the flow of charge

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

What is the equation for resistivity

A

Resistivity = resistance X area / length

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

what is the rule for current in a series circuit

A

series circuit, the current is the same for all components

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

what is the rule for p.d in series circuit

A

p.d is shared between all components

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

what is the rule for resistance in series circuit

A

total resistance is the sum of all resistances

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

what is the rule for p.d in parallel circuit

A

p.d for cell/battery is the p.d for each branch

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

what is the rule for current in parallel circuits

A

the current is split between the branches

19
Q

what is the rule for resistance in parallel circuits

A

The sum of the resistance in parallel circuits is equal to the sum of the inverse of each individual resistances

1/Rt= 1/R1 + 1/R2 + 1/R3

20
Q

what is resistance

A

the opposition to current

21
Q

What is drift velocity

A

The net movement of electrons

22
Q

Resistance =

A

Potential difference/current

23
Q

Kirchhoff’s second law

A

The sum of the e.m.f is equal to the sum of the potential difference in series

24
Q

What is potential difference

A

The work done per unit charge

25
Q

What is one coulomb

A

The amount of charge that passes in 1 second when the current is 1 amp

26
Q

Energy transferred electricity equations

A

W=VQ

27
Q

Define potential difference of 1 volt

A

1 joule of energy transferred per coulomb

28
Q

What is the mean drift velocity

A

The average velocity of the charge carriers

29
Q

What is the mean drift velocity equation

A

I = Anev

Current = Cross sectional area x number density of electrons x size of charge in one electron x mean drift velocity’s

30
Q

Equation for resistance is

A

R= V/I

31
Q

What 3 things does resistance depend on?

A

-Length(L) the longer the wire the more difficult it is for current to flow

-Area (A) the wider the wire the easier it will be for electrons to pass through

-Resistivity (ρ) depends on material wire is made from how easy electrons flow through a material

32
Q

Resistivity definition and unit

A

The resistance of a 1m length with a 1m^2 cross-sectional area

-Ohmmeters is unit

33
Q

What is ohms law

A

If the temperature is constant the current through an ohmic conductor is directly proportional to the potential difference

34
Q

Why is the I-V characteristic for a metallic conductor a straight line

A

-At a constant temperature the current is directly proportional to the potential difference

  • metallic conductors are ohmic- they have constant resistance just so long as the temperature doesn’t change
35
Q

Why is it characteristic for lamp curved

A

Current flowing though lamp increases its temperature. So the resistance increases

36
Q

Why does the resistance of a metal increase with temperature

A

Heating makes it harder for electrons to move about. The ions vibrate more when heated so the electrons collide with them more often. Ionising energy gets lost to other forms

37
Q

Why do semi conductors resistance decrease as the potential difference increases

A

Semi conductors have higher resistance because there are fewer charge carriers available.

If energy is supplied more charge carriers are released so resistivity decreases.

So they are good for detecting changes

38
Q

Power definition

A

Power is the rate of transfer of energy or one joule of work done per second

39
Q

Formula for power in electrical circuits

A

P=IV

40
Q

Give equation 2 for power

A

Power = (Voltage)^2 / Resistance
P= I^2 R

41
Q

Give Equation 3 for power

A

Power = (Current)^2 X Resistance

42
Q

An equation for power that links work done and time

A

P= W ÷ t
Power = work done ÷ time

43
Q

Explain how voltage is affected when temperatures change for thermistors

A

componentAs temperature of thermistor increases, resistance of thermistor decreases

Total resistance of circuit decreases and current increases

Greater proportion of p.d. across fixed resistor

Reading on the voltmeter will increase

44
Q

Copper is a metal, carbon is a semiconductor and ceramic is an insulator.
Describe the difference between these three materials in terms of the number density n free electrons. Include an explanation of the term number density.

A

n = number of (free) charge carriers per unit volume

The larger the value of n, the better the conduction

Copper has a larger n than carbon which has a larger n than ceramic

Physics A-level (10 decks)

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