P4 Electric circuits Flashcards

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1
Q

What makes up electricity

A

electrons

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2
Q

define current

A

the rate of flow of charge

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3
Q

What is the unit for current

A

Amps (A)

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4
Q

What is voltage

A

the amount of energy per charge

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5
Q

What is the unit for voltage

A

Volts (V)

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6
Q

What does resistance do

A

slow the current down, resisting the flow of charge

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7
Q

What is resistance measured in

A

Ohms (Ω)

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8
Q

Define ohms law in a sentence

A

Voltage and current are directly proportional (r=v/i)

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9
Q

When does more charge pass around a circuit

A

when a larger current flows

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10
Q
A

ammeter

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11
Q
A

bulb

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12
Q
A

buzzar

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13
Q
A

cell

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14
Q
A

diode

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15
Q
A

LDR

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16
Q
A

LED

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17
Q
A

motor

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18
Q
A

resistor

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19
Q
A

switch

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20
Q
A

thermistor

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21
Q
A

variable resistor

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22
Q
A

voltmeter

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23
Q
A

battery

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24
Q

What makes something and ohmic conductor

A

its current flowing through is directly proportional to the potential difference (voltage) across it

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25
Q

Give an example of an ohmic conductor

A

a wire
a resistor

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26
Q

describe what a graph of a wire would be like

A

the voltage and current are directly proportional

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27
Q

Why does resistance change in a filament bulb

A

because of the heating effect

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28
Q

What happens in the heating affect

A
  • collisions between electrons and metal ions
  • friction caused
  • causes heat which
  • increases resistance
29
Q

what does the resistance of a diode depend on

A

the direction of the current

30
Q

Why does the resistance of a diode depend on the direction of the current

A

because they will let current flow one direction but have a very high resistance in the other direction

31
Q

What does the term ‘I-V characteristics’ refer to

A

a graph which shows the current flowing through a component changes as the potential difference is increased

32
Q

what I-V characteristics do linear components have

A

straight line

33
Q

what I-V characteristics do non-linear components have

A

a curved line

34
Q

describe the relationship of an I-V graph of a filament bulb

A

It starts directly proportional, overtime the gradient slowly decreases - the resistance increases

35
Q

Why does the resistance start to increase in an I-V graph of a filament bulb

A

because of the heating effect

36
Q

in an I-V graph how does resistance and gradient relate

A

as gradient goes down (flatter) resistance goes up

37
Q

What is LDR short for

A

Light dependent resistor

38
Q

what is an LDR

A

a resistor that is dependent on the intensity of light

39
Q

How does light affect the resistance in an LDR

A

as light intensity increases resistance decreases (lurd)

40
Q

What does resistance in a thermistor depend on

A

temperature

41
Q

How does temperature affect the resistance in a thermistor

A

As temperature increases resistance decreases (turd)

42
Q

What type of graph is this

A

a diode I-V graph

43
Q

What type of graph is this

A

a filament bulb I-V graph

44
Q

What type of graph is this

A

A wire I-V graph

45
Q

What type of graph is this

A

An LDR graph

46
Q

What type of graph is this

A

a thermistor graph

47
Q

what can you use LDRs and thermistors in

A

sensing circuits

48
Q

What are sensing circuits

A

circuits that can be used to turn on or increase the power to components depending on the conditions they are in

49
Q

What path does electricity take

A

the one with the least resistance

50
Q

Describe the appearance of series circuits

A

They are one loop and all of the components are connected in a line, end to end

51
Q

What is potential difference (voltage) like in series circuits

A

it is shared between various components
the pd of all the components will add up to the total

52
Q

what is current like in series circuits

A

it is the same everywhere
the size of the current is determined by the total pd and resistance

53
Q

what is resistance like in a series circuit

A

the total resistance is the sum of the resistance in the components

54
Q

why is the total resistance in series circuit the sum of the resistance in components

A

because the components have to share the potential difference (voltage)

55
Q

describe the appearance of a parallel circuit

A

it is multiple loops where each component is separately connected

56
Q

what is potential difference (voltage) like in parallel circuits

A

there is the same amount of voltage for everything - the pd is the same across all components

57
Q

what is current like in parallel circuits

A

it is shared - the total current flowing in the circuit is equal to the total currents through separate loops (components)

58
Q

How do work out Rt for a parallel circuit

A

1/Rt = 1/R1 + 1/R2
then flip answer to get Rt/1

59
Q

what is static electricity caused by

A

friction

60
Q

What happens when static electricity is formed

A
  • insulating materials are rubbed together
  • electrons will transfer to one of the materials (they are oppositely charges)
61
Q

What happens with a polythene rod

A

gains electrons - becoming negatively charged

62
Q

What happens to a acetate rod

A

it loses electrons - becoming positively charged

63
Q

why do insulators not lose its charge

A

because they don’t have free electrons

64
Q

why does static electricity form sparks

A

because the potential difference gets large enough to jump across the gap between the charged object and earth

65
Q

opposite charges…

A

attract

66
Q

Same charges…

A

repel

67
Q

What will happen to the total resistance in a parallel circuit if you add a resistor

A

the total resistance will decrease because the current has increased

68
Q

What is the equation for voltage current and resistance

A

V= IR