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physics paper 1 > electricity > Flashcards

electricity Flashcards

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1
Q

what is electric current?

A

Electric current is the flow of electrical charge

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2
Q

what is current measured in?

A

amps

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3
Q

what is electrical charge measured in?

A

coulombs

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4
Q

electrical charge equation:

A

charge flow = current x time

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5
Q

what is the resistance of a component?

A

Resistance of a component is the measure of how it resists the flow of charge

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6
Q

the higher the resistance:

A
  • the more difficult for charge to flow

- the lower the current

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7
Q

what is resistance measured in?

A

ohms

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8
Q

what does potential difference tell us?

A

potential difference tells us the difference in electrical potential from one point at a circuit to another

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9
Q

the bigger potential difference across a component:

A
  • the greater flow of charge through

- the bigger the current

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10
Q

what is potential difference measured in?

A

volts

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11
Q

potential difference equation

A

potential difference= current x resistance

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12
Q

what does a current graph show?

A

a current graph shows the relationship between potential difference and current for any component

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13
Q

resistor graph:

A

straight line graph

resistance remains constant

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14
Q

filament lamp graph:

A

indicated by a curved graph

resistance increase as current increases

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15
Q

diodes graph:

A

horizontal line along x axis

no current flows

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16
Q

what happens to the resistance of a thermistor?

A

The resistance of a thermistor the decreases as the temperature increases

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17
Q

what happens to the resistance of an LDR?

A

The resistance of an LDR decreases as light intensity increases

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18
Q

what happens in a SERIES circuit?

A

in a series circuit:
current: STAYS the same
potential difference: SHARED

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19
Q

what happens in a PARALLEL circuit?

A

in a parallel circuit:
current: SHARED
potential difference: NOT shared

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20
Q

what happens if a component in a SERIES circuit breaks or is removed??

A

the rest of the components WILL NOT work

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21
Q

what happens if a component in a PARALLEL circuit breaks or is removed??

A

the rest of a component WILL continue to work

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22
Q

what does the power of a device depend on?

A

The power of a device depends on the potential difference across it and the current flowing through it.

23
Q

a device with higher potential difference will….

A

use more energy per second

more powerful

24
Q

2 equations for POWER

A

power= potential difference x current

power=(current)2 x resistance

25
Q

DIRECT current potential difference:

A

DIRECT

  • one is always positive or always negative
  • > makes current constant
26
Q

when is DIRECT current used?

A

direct current is supplied by cells and batteries

27
Q

ALTERNATING current potential difference:

A

ALTERNATING

  • alternates from positive to negative
  • > makes current direction alternate
28
Q

when is ALTERNATING used?

A

alternating current is used in mains electricity

29
Q

what colour is live wire?

A

love wire is brown

30
Q

what colour is neutral wire?

A

neutral wire is blue

31
Q

what colour is earth wire?

A

earth wire is green and yellow

32
Q

components of a plug

A
  • fuse
  • cable grip
  • cable
  • live wire
  • neutral wire
  • earth wire
33
Q

when is the earth wire used?

A

current will only flow in the Earth wire if there is a fault
(safety wire)

34
Q

what does the live wire do?

A

The livewire carries the alternating potential from the supply

35
Q

What does the neutral wire do?

A

The neutral wire complete the circuit by carrying the current away from appliance

36
Q

what are the V of each wire?

A

LIVE: 230v
NEUTRAL: 0v
EARTH:0v

37
Q

what are the dangers of mains electricity?

A

electric shock can be fatal

38
Q

what happens if u touch a live wire?

A

if you touch a live wire it creates large potential difference across the body

39
Q

what is power?

A

Power is the rate at which energy is transferred or work is done

40
Q

2 power equations:

A

power= energy transferred
—————————
time

power= work done
——————
time

41
Q

what is efficiency?

A

Efficiency is the ratio of useful energy out to the total energy in

42
Q

efficiency of 0.75 (75%) means…

A

3/4 =useful

1/4 =wasted

43
Q

2 efficiency equations:

A

efficiency= Useful energy transfer
———————————
total energy transfer

efficiency= useful power output
——————————
total power input

44
Q

what happens when charge flows?

A

when charge flows

  • work is done
  • > which depends on the amount of charge that flows and potential difference
45
Q

2 energy transferred equations

A

energy transferred= power x time

energy transferred= charge flow x potential difference

46
Q

what is the national grid?

A

The National Grid is a system of cables and Transformers linking power stations to homes and businesses

47
Q

what does the power station do?

A

power stations transfers the energy supply into electrical energy

48
Q

to make power stations more efficient you…

A

use a smaller number of large power stations

49
Q

why is using larger power stations more efficient?

A

using large power stations is more efficient because most power plants use steam turbines which are more efficient at higher steam temperatures

50
Q

what do transmission cables do?

A

transmission cables transfers electricity

51
Q

what does step up transformers do?

A

step up transformers increase the potential difference from the powerstation to the transmission cables

52
Q

why are step up transformers good?

A

they reduce the current which reduces the heating effect caused by the current flowing in the transmission cables

53
Q

what does reducing the heating effect do?

A

reducing the heating affect reduces energy loss to make the transmission more efficient

54
Q

what does step down transformers do?

A

Stepdown transformers reduce the potential difference from the transmission cables to a much lower value for domestic use

physics paper 1 (5 decks)

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