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A Level Physics > Electrical Charge Transfer > Flashcards

Electrical Charge Transfer Flashcards

1
Q

P.D definition

A

the amount of energy transferred from electrical to other forms of energy per unit charge

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2
Q

resistance definition

A

the amount of opposition against current & equatioon

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3
Q

coulomb definiiton

A

the charge in a current powered by 1V

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4
Q

what happens to resistance in a parralel circuit

A

resistance decreases, due to increase in branches

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5
Q

what is the definition of drift velocity

A

the average velocity of electrons when there is an APPLIED ELECTRIC FIELD

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6
Q

number density units

A

m^-3

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7
Q

what is conventional current

A

the flow of positive charge, from the positive terminal to the negative terminal

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8
Q

electron flow definition

A

the flow of negative charge from the negative terminal to the positive terminal

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9
Q

what does Kirchoff’s first law prove: conservation of…

A

conservation of charge

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10
Q

definition of e.m.f

A

The energy transferred from chemical to electrical per unit charge

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11
Q

definition of p.d

A

The energy transferred from electrical energy to other forms (e.g heat, light) per unit charge

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12
Q

what does the gradient of a IV-characteristic graph represent?

A

1/resistance

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13
Q

ohms law definition

A

p.d is directly proportional to current, assuming TEMPERATURE OF CONDUCTOR IS CONSTANT

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14
Q

how is ohms law represented on a graph?

A

straight line which passes through origin

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15
Q

name 3 ways to change resistance of a wire in a circuit

A

type of material, shape of wire, temperature of wire

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16
Q

resistivity equation

A

resistance = (resistivity * length ) / area

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17
Q

units for resistivity

A

ohm meters

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18
Q

resistance defintiion

A

write R= I/V in words and say ‘ the amount of opposition against current’

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19
Q

resistivity definition

A

write the equation & “a measure of how strongly a material opposes the flow of current”

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20
Q

what is extraneous light (LDR section)

A

light from an exteral light source

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21
Q

what happens to a NTC thermistor when there’s a rise in temperature?

A

releases more charge carriers, hence reducing the resistance. The increase in vibrations of particles has a lower impact on the resistance - net decrease in charge.

22
Q

what are the 2 things that could happen in a component that could impact its resistance when temperature increases

A
  • increase in number of charge carriers - decrease resistance
  • increase in vibrations (of positive ions) leads to more collisions - increasing resistance
23
Q

for a NTC thermistor, when temperature increases, resistance …

A

decreases

24
Q

for an LDR, when light intensity increases, resistance ….

A

decreases

25
Q

What does ‘e’ stand for

A

Elementary charge - charge on 1 electron

26
Q

what is Kirchoff’s first law?

A

the sum of current entering a junction is equal to the sum of the current exiting it

27
Q

current definition

A

rate of flow of charge

28
Q

what is the charge of a single electron (e)? single proton?

A

electron: 1.6x10^-19
proton: 1.6x10^19

29
Q

number density definition

A

no. of free electrons per m^3 of a specific material

30
Q

what is an electron gun used fore?

A

A device that uses a large accelerating p.d to produce a narrow beam of electrons

31
Q

how do electron guns work

A

small metal filament is kept in a vacuum with a high p.d. (1)
It is heated by electric current. (2)
Some electrons gain enough K.E to escape metal and accelerate to anode. (3)

32
Q

light intensity units and equation?

A

lux; l is directly proportional to 1/distance^2`

33
Q

give a similarities between thermistor and LDR

A

when temp/ligth intensity increases, resistance decreases

34
Q

are thermistors and LDR’s conductors, semi-conductors or insulators?

A

semi-conductors

35
Q

which of these has highest number density: insulators, semi-conductors, conductors

A

conductors

36
Q

what is the mass of an electron

A

9.11x10^-31

37
Q

true or false, thermistors and LDR’s are ohmic conductors

A

false

38
Q

describe the structure of metal (in a wire)

A

a regular crystal structure of postive ions surrounded by a no. of free electrons

39
Q

what material is often used in computer processors and why?

A

silicon because it’s a good semi-conductor

40
Q

conservation of charge definition

A

the net charge must be the same before and after an interaction; charge carriers can’t be created or destroyed

41
Q

what does the gradient of an IV graph represent

A

1/resistance

42
Q

name 3 things that could impact resistance in a circuit

A

type of material, shape of material, temperature of wire

43
Q

IV characteristic of thermistor? of LDR?

A

search it up

44
Q

electronvolt defintiion

A

A unit of energy. (1) the energy transfered to or from an electron when it passes theough a p.d of 1 volt. 1eV = 1.6x10^-19J

45
Q

1eV is equal to … J

A

1.6x10^-19J

46
Q

what is the equation of eV

A

eV=1/2mv^2

47
Q

what happens to electrons eneergy in electron gun/cathode ray tube when p.d increases

A

increase in energy = increase in speed of leectons

48
Q

what will happen to electrons speed in a cathode ray tube/ electron gun when there’s no p.d?

A

speed of electron will be constant (not stationary)

49
Q

where does electron accelerate in cathode ray tube? where is the speed constant?

A

accelerates between anode and cathode

constant between anode and screen

50
Q

what are the advantages of using a data logger (4)

A

1) continuous record for a long time scale
2) records v.short time scale
3) automatic recording
4) data can be fed into computer for analysis

A Level Physics (6 decks)

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