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Electricity Flashcards

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1
Q

What is current?

A

Flow of electrical charge.

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2
Q

What is the unit for current?

A

Ampere, A.

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3
Q

What is potential difference?

A

Driving force that pushes charge round.

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4
Q

What is the unit for potential difference?

A

Volt, V.

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5
Q

What is resistance?

A

Anything that slows down charge flow.

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6
Q

What is the unit for resistance?

A

Ohm, Ω.

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7
Q

What are the two factors that current through a component depend on?

A

> the component’s resistance.
↳ the greater the resistance, the smaller the current.
the potential difference across the component.
↳ the greater the potential difference, the larger the current (for a fixed resistance).

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8
Q

What is the size of current the same as?

A

Rate of flow of charge.

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9
Q

What is the formulae for charge flow?

A

Q = It
charge flow = current x time

[coulombs (C) = amps (A) x secs (S)]

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10
Q

What is the formulae for potential difference?

A

V = IR
potential difference = current x resistance

[volts (V) = amps (A) x ohms (Ω)]

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11
Q

Draw the circuit symbol of a cell.

A

Check your answer in your knowledge organiser (pg 83)

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12
Q

Draw the circuit symbol of a battery.

A

Check your answer in your knowledge organiser (pg 83)

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13
Q

Draw the circuit symbol of a open switch.

A

Check your answer in your knowledge organiser (pg 83)

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14
Q

Draw the circuit symbol of a voltmeter.

A

Check your answer in your knowledge organiser (pg 83)

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15
Q

Draw the circuit symbol of an ammeter.

A

Check your answer in your knowledge organiser (pg 83)

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16
Q

Draw the circuit symbol of a closed switch.

A

Check your answer in your knowledge organiser (pg 83)

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17
Q

Draw the circuit symbol of a resistor.

A

Check your answer in your knowledge organiser (pg 83)

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18
Q

Draw the circuit symbol of a variable resistor.

A

Check your answer in your knowledge organiser (pg 83)

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19
Q

Draw the circuit symbol of a filament lamp (or bulb).

A

Check your answer in your knowledge organiser (pg 83)

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20
Q

Draw the circuit symbol of a diode.

A

Check your answer in your knowledge organiser (pg 83)

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21
Q

Draw the circuit symbol of a LDR.

A

Check your answer in your knowledge organiser (pg 83)

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22
Q

What does LDR stand for?

A

Light-dependent resistor.

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23
Q

Draw the circuit symbol of a thermistor.

A

Check your answer in your knowledge organiser (pg 83)

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24
Q

Draw the circuit symbol of a LED.

A

Check your answer in your knowledge organiser (pg 83)

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25
Q

What does LED stand for?

A

Light-emitting diode.

26
Q

Draw the circuit symbol for fuse.

A

Check your answer in your knowledge organiser (pg 83)

27
Q

What do the straight lines connecting the components represent?

A

Wires.

28
Q

What are the three different current devices?

A

> ohmic conductor such as a resistor at constant temperature.
filament lamp.
diode.

29
Q

What happens to the resistance in a ohmic conductor?

A

It doesn’t change as current is directly proportional to potential difference.

30
Q

Is a ohmic conductor’s graph linear or non-linear?

A

Linear.

31
Q

What happens to the resistance in a filament lamp?

A

The resistance increases as the temperature of filament increases due to the current increasing.

32
Q

Is the filament lamp graph linear or non-linear?

A

Non-linear.

33
Q

What happens to the resistance in a diode?

A

The resistance is high in one direction so the current only flows in the other direction.

34
Q

Is the diode graph linear or non-linear?

A

Non-linear.

35
Q

Draw the graph of a ohmic conductor.

A

Check your answer in your knowledge organiser (pg 84)

36
Q

Draw the graph of a filament lamp.

A

Check your answer in your knowledge organiser (pg 84)

37
Q

Draw the graph for a diode.

A

Check your answer in your knowledge organiser (pg 84)

38
Q

What components have changing resistance (when current though them varies)?

A

> filament lamp (or bulb).
diode.
LDR.
thermistor.

39
Q

When using an LDR, what does the resistance depend on?

A

Light intensity.

40
Q

When using an LDR, there is lower resistance in…

A

…brighter light.

41
Q

What is LDR used in?

A

Automatic night lights.

42
Q

When using a thermistor, resistance depends on?

A

Temperature.

43
Q

When using a thermistor, there is lower resistance in…

A

…hotter temperatures.

44
Q

What can you find a thermistor in?

A

Thermostats.

45
Q

Explain what happens in a series circuit.

A

> current is the same everywhere.
↳ I₁ - I₂
total source potential difference is shared between components.
↳ (total) V = V₁ + V₂
Total resistance of components = sum of their resistances.
↳ (total) R = R₁ + R₂
adding a resistor in a series circuit increases the total resistance of the circuit.

46
Q

Explain what happens in a parallel circuit.

A

> total current flowing around a circuit = sum of the currents through each branch.
↳ (total) I = I₁ + I₂
potential difference across each branch in the same as the source potential difference.
↳ V₁ = V₂ = V (total)
adding a resistor in a parallel circuit decreases the total resistance of the circuit.

47
Q

What does AC stand for?

A

Alternating current.

48
Q

What is alternating current?

A

Current that constantly changes direction and is produced by an alternating voltage.

[used in mains supply]

49
Q

What does DC stand for?

A

Direct current.

50
Q

What is direct current?

A

Current that always flows in the small direction and is produced by a direct voltage.

[supplied by batteries]

51
Q

What are three facts about the UK mains?

A

> ac supply.
frequency of 50 Hz.
voltage around 230 V.

52
Q

What are the three wires in a three-core cable called?

A

> live wire.
neutral wire.
earth wire.

53
Q

Describe the live wire.

A

> brown.
potential difference is at 230 V.
it is used to provide alternating potential difference from mains supply.

54
Q

Describe the neutral wire.

A

> blue.
potential difference is at around 0 V.
it is used to complete the curcuit.

55
Q

Describe the earth wire.

A

> green and yellow.
potential difference is at 0 V.
it is used to stop appliance casing becoming live.

56
Q

What happens when a body is electrocuted?

A

① the body has 0V whilst a wire can hold 230V.
② ones touched, large potential difference is produced across the body.
③ Curren flows through the body.

57
Q

What are the two formulaes for energy transferred?

A

E = QV
energy transferred = charge flow x potential difference

[joules (J) = current (C) x voltage (V)]

OR

E = Pt
energy transferred = power x time

[joules (J) = watts (W) x secs (S)]

58
Q

What does the amount of energy an appliance transfers depend on?

A

> appliance’s power.

> how long appliance is on for.

59
Q

What is power?

A

Energy transferred per second.

60
Q

What is power rating?

A

The maximum safe power an appliance can operate at.

61
Q

What are the two formulaes for power?

A 
P = VI
power = potential difference x current

[watts (W) = voltage (V) x amps (A)]

OR

P = I²R
power = current² x resistance

[watts (W) = amps (A)² x ohms (Ω)

physics. (10 decks)

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