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Physics Unit 2 + 3 > Unit 2 - Electrical Circuits > Flashcards

Unit 2 - Electrical Circuits Flashcards

0
Q

What does a Voltmeter measure?

A

Measures voltage/potential difference (v/volts)

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1
Q

What does an ammeter do?

A

Measures current - in amperes (A)

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2
Q

How is an ammeter connected to the circuit?

A

It is always connected into the circuit

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3
Q

How is the voltmeter connected to the circuit?

A

It is connected across a component in parallel

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4
Q

What is the pd across all the cells equal to?

A

The sum of the pd’s across the bulbs in a series circuit

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5
Q

The current is the same whenever..?

A

..you measure it in a series circuit

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6
Q

What do more cells give the circuit?

A
  • Bigger p.d
  • Bigger current
  • Brighter bulb
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7
Q

What does more bulbs give the circuit?

A
  • Lower current
  • Dimmer bulbs
  • Pd per bulb decreases
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8
Q

What happens to all the bulbs in a series circuit if 1 goes out?

A

All the others also go out

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9
Q

What happens to the bulbs in a parallel curcuit if one goes out?

A

They stay lit

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10
Q

How many paths for the current in a seriews circuit?

A

Only 1

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11
Q

How many paths for the current in a parellel circuit?

A

More than 1

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12
Q

What is this?

A

A cell

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13
Q

What is this?

A

A battery

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14
Q

What is this?

A

An open switch

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15
Q

What is this?

A

A closed switch

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16
Q

What is this?

A

A filament lamp

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17
Q

What is this?

A

An Ammeter

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18
Q

What is this?

A

A Voltmeter

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19
Q

What is this?

A

LDR (light-dependant resistor)

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20
Q

What is this?

A

A diode

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21
Q

Whats this?

A

An LED (light emitting diode)

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22
Q

Whats this?

A

A fuse

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23
Q

Whats this?

A

A resistor

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24
Q

Whats this?

A

A variable resistor

25
Q

Whats this?

A

A thermister

26
Q

What is the current?

A

The rate of flow of charge

27
Q

What is the potential difference?

A

The pd between 2 points in an electric circuit is the work done (energy transferred) per coulomb of charge that passes between the points

28
Q

Resistance

A

A measure of how hard it is for a current to pass through any component

29
Q

What is the total resistance in a circuit?

A

R1+R2 (resistors added together)

30
Q

What is the total pd in a circuit?

A

the pd’s added together

31
Q

When calculating the pd, if each cell =1.5V and the cells are facing the same way what is the total pd?

A

1.5+1.5 = 3V

32
Q

When calculating the pd, if each cell =1.5V and the cells are facing opposite eachother what is the total pd?

A

1.5V-1.5V = 0V

33
Q

Factors that effect resistance?

A
  • Material
  • Cross sectional area (thickness)
  • Temperature
  • Length
34
Q

In terms of resistance - the longer the wire?

A

The more resistance

35
Q

In terms of resistance - thinner wire =?

A

More resistant

36
Q

In terms of resistance, the thicker the wire?

A

The lower the resistance

37
Q

What does ohms law state?

A

The current through a fixed resistance will be proportional to the pd across the resistor providing the temoerature is constant

38
Q

What is the equation for the resistace?

A

R = I/V

resistance = current / pd

39
Q

Whats the equation for the gradient?

A

Rise

step

40
Q

What is the use of a diode?

A

Only allows current to flow thorugh in one direction so it can be used to protect electronic circuits

41
Q

Whats the difference between a conducting and unconducting diode?

A
42
Q

Use of an LDR

A

Can be used to control circuits as light sensors/automatically switches light etc because its **resistances changes **as the **light intensity changes **

43
Q

Use of a thermistor?

A

In central heating systems as part of the thermostat of any circuit to control temperature because its resistance varies with temperature

44
Q

Whats the use of LED’s?

A
  • In small scale lighting eg on electronic equipment
  • In low power lighting in buildings
  • **Brake lights ** because their long loved and very reliable
45
Q

Static electricity: Two like charges..?

A

Repel

46
Q

Static electricity: two unlike charges..?

A

Attract

47
Q

Electrons (which are negative) can move from one ____?____ to another due to ?

A

From one insulator to another due to rubbing/friction

48
Q

What happens if something looses electrons?

A

It becomes positively charged

49
Q

What happens if something gains electrons?

A

It will bcome negatively charged

50
Q

What is the frequency and voltage of the mains electricity we use?

A

Voltage - 230V

Frequency - 50Hz

51
Q

What is an alertnating current?

A

An electric current that continually changes its direction

52
Q

Whats a direct current?

A

An electric current that flows in the same direction at all times

53
Q

What is another source of electricity we use thats not mains?

A

Batteries, these have no frequency and have a direct current

54
Q

What happens when a current passes through a resistor?

A

Heat energy is produced

(it can be good though eg kettle, iron)

55
Q

How is a point of high resistance caused?

A

By damage in a wire, it can cause overheating

56
Q

Why are ovens etc connected by thick wires?

A

So that the large current doesnt cause overheating

57
Q

What happens when a large current pases through a thin fuse wire?

A

The wire melts and breaks the circuits

58
Q

Whats the equations for normal current?

A

Power

_________

Voltage

59
Q

Whats a RCCB and how does it work

A

Residual current circuit breaker

it works by comparing the current in the live and neutral wires if the icrrents are different they break the circuits up

60
Q

What are the advantages of an RCCB?

A

Resettable (less mistakes made by changing fuses manually)

Faster

61
Q
A

Physics Unit 2 + 3 (13 decks)

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