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Physics > Electricity > Flashcards

Electricity Flashcards

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1
Q

A circuit diagram shows how ____ are connected together

A

Components

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2
Q

For components in series, the potential differences ____ to give the total potential difference.

A

Add up

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3
Q

The resistance of a filament lamp ____ with increase of the filament texture.

A

Increases

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4
Q

Resistance (Ohms) =

A

Potential difference (Volts)
Resistance (Ohms) = —————————-
Current (Amps)

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5
Q

The current through a resistor at constant temperature is directly _____ to the potential difference across the resistor.

A

Directly proportional

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6
Q

For components in parallel, the potential difference is ____ in each component.

A

The same

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7
Q

A ____ consists of two or more cells connected together.

A

A battery

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8
Q

For components in series, the resistances ____ to give the total resistance.

A

Add up

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9
Q

For a diode, its ‘forward’ resistance is ____ and its ‘reverse’ resistance is ____.

A

Forward resistance s low and reverse resistance is high

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10
Q

For components in parallel, the total current is the ____ of the currents through each component.

A

Total

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11
Q

The resistance of a thermistor decreases if its temperature ____.

A

Increases

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12
Q

For components in parallel, the bigger the resistance of a component, the ____ the current is.

A

Smaller

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13
Q

Charge (Coulombs) =

A

Charge (Coulombs) = Current (A) x Time (s)

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14
Q

Where would you get a direct current?

A

From a cell or battery

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15
Q

List good electrical conductors

A

Silver, Copper, Graphite, Other metals etc

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16
Q

Describe lightning in terms of the movement of electrons

A

A charge builds up in water droplets in a cloud due to friction. This can induce an opposite charge in tall objects, leading to electrostatic attraction. The electrons are attracted and ‘jump’ as an electrostatic discharge.

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17
Q

What are the units for the equation, Power = Current x Voltage

A

Watts = Amps x Volts

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18
Q

List some common insulating materials

A

Glass, plastic, wood, rubber, fabric etc

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19
Q

Energy transferred=

A

Energy transferred (J)= Current (A) x Voltage (V) x Time (seconds)

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20
Q

List and describe some danger of electrostatic charges

A

Fuelling aircraft or tankers: A build up of too many electrons can discharge as a spark, causing a fire or explosion.

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21
Q

Which appliance allows current to flow more when the temperature increases?

A

Thermistor

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22
Q

Energy transferred (J) =

A

Energy transferred (J) = Power (Watts) x Time (s)

23
Q

Why is a parallel circuit more suitable for domestic lighting? Give two reasons.

A
  • The lights can be switched on/off independently

- Any broken bulb will not effect the whole circuit.

24
Q

Electrical power supplied (Watts)=

A

Electrical power supplied (Watts)= Current (A) x Potential difference (V)

25
Q

Why does a rubbed balloon make your hair stick up?

A

The rubbing causes a movement of electrons, leaving a static charge. This charge induces the opposite charge in the hair, causing an electrostatic attraction.

26
Q

What is the difference between electricity and electrostatics?

A

Electricity: In conducting materials, electrons flow when given energy by a power supply.

Electrostatics: In insulating materials, electrons moved by friction, charge builds up

27
Q

An electric current is a flow of ____

A

Electrons/ Negative charge

28
Q

What are the properties of mains current?

A
  • Alternating Current
  • 50Hz
  • 230V
29
Q

What type of material can be charged by friction?

A

Insulating materials

30
Q

List and describe some uses of electrostatics

A

Laser copier/ printer: The image is ‘drawn’ by laser leaving a charge. The ink particles are given the opposite charge and stick to the place, then heated on.

Inkjet printer/ paint gun/ crop sprayer: Particles are given a charge so that they repel each other and give an even coverage without clumping

31
Q

What types of material does static electricity build up in?

A

Any insulator

32
Q

Is the current and the potential difference the same all the way around a series circuit?

A

Yes, the current is the same but the voltage is not

33
Q

The power supplied to a device is the energy transfer to it every ____.

A

Second

34
Q

If you increase the resistance of a circuit, what happens to the current?

A

Decreases, V=IR

35
Q

What is an electrostatic charge?

A

When friction causes a transfer of electrons. This creates a negative charge where they build up, and a positive charge where they were moved from.

36
Q

Describe some safety features of electrical devices

A

Fuses, circuit breakers, earthing, insulating materials etc

37
Q

What is the power of a mains lamp that needs 5 amps to run it?

A 
Power = Current x Voltage
Power = 5 x 230
Power = 1150W
38
Q

When charge flows through a resistor, electrical energy is transferred as ____

A

Heat or thermal energy

39
Q

What affects the size of the current in a series circuit?

A

The voltage, and the number and the resistance of the components in the circuit.

40
Q

When an insulating material is rubbed, what particles move?

A

Electrons

41
Q

List some hazards of using electricity

A
  • Frayed cables
  • Long cables cause a trip hazard
  • Water around sockets
  • Fingers/ objects pushed into plugs
  • Electrocution
42
Q

Sockets, plugs, wire casing and some electrical devices are made of ____ materials for safety reasons.

A

Insulating

43
Q

What is voltage?

A

The energy transferred per unit of charge passed, ie a Joule per Coulomb

44
Q

Opposite charges ____

A

Attract

45
Q 
What fuse should I choose if I want to light a 60W bulb in a 19V circuit?
1A
3A
5A
13A
A

5 amps

46
Q

A fuse contains a thin wire that heats up, melts and breaks the circuit if ____ current passes through it.

A

Too much, or more current than the fuses value

47
Q

Current is

A

The rate of flow of negative charge

48
Q

Like charges

A

Repel

49
Q 
Which fuse should I choose if I want to light a 40W bulb in a 4V circuit?
1A
3A
5A
13A
A

13A

50
Q

The resistance of an LDR ____ if the light intensity on it increases.

A

Decreases

51
Q

Mains electricity is an alternating current supply. Alternating current repeatedly _____ its direction

A

Reverses

52
Q

For components in series, the current is ____ in each component.

A

The same

53
Q

Cables consist of two or three insulated wires made of ____

A

Copper

54
Q

How many blondes does it take to change a lightbulb?

A

None

Physics (8 decks)

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