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Revision > Physics > Flashcards

Physics Flashcards

1
Q

What are the energy stores

A

Nuclear
Thermal
Magnetism
Kinetic
Gravitational potential
Elastics potential
Chemical
Electrostatic

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2
Q

What do Vectors have

A

Magnitude and direction

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3
Q

What do scalars have

A

Magnitude

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4
Q

formula for specific heat capacity

A

change in thermal energy / change in temp * mass

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5
Q

what is power

A

the rate of energy transfer or doing work

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6
Q

how do you calculate power

A

energy transferred/time

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7
Q

what is conduction

A

The process in which vibrating particles transfer energy

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8
Q

what is the formula for charge

A

current*time

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9
Q

what is the voltage of the uk mains supply

A

230v

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10
Q

what is AC current

A

when the current is constantly changing directions

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11
Q

what type of current does the mains supply supply

A

AC

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12
Q

what type of current does a battery supply

A

DC

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13
Q

what is DC current

A

current that is always flowing in the same direction

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14
Q

what are the three wires cables have

A

neutral
live
earth

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15
Q

What is the job of the neutral wire

A

completes circuit

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16
Q

what is the job of the Earth wire

A

protecting wiring- safety- stops appliance casing from becoming live

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17
Q

What is the Job of the live wire

A

provides the alternating potential difference

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18
Q

What is the colour of the live wire

A

brown

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19
Q

what is the colour of the Earth wire

A

yellow and green

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20
Q

what is the colour of the neutral wire

A

blue

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21
Q

What is specific heat capacity

A

Specific heat capacity is the amount of energy needed to raise the temperature of a kg of a substance by 1 degrees

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22
Q

What is conduction

A

the process in which vibrating particles transfer energy to neighbouring particles.

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23
Q

What is Convection

A

the process in which energetic particles move from hotter to cooler regions

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24
Q

Positives of wind power

A

minimum maintenance costs

no pollution

no fuel costs

no permanent damage to landscape

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25
Q

Negatives of Wind power

A

not reliable

high start up costs

not reliable

eye sore

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26
Q

Positives of Solar cells

A

running costs very small

no pollution

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27
Q

Negatives of solar cells

A

high start up costs

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28
Q

What is Current

A

Current is the flow electricity

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29
Q

What is potential difference

A

driving force that pushes the current around measured in volts

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30
Q

What is resistance

A

anything in the circuit which slows the flow of electricity down

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31
Q

What resistance do ohmic conductors have

A

constant resistance

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32
Q

What does it mean if an ohmic conductor has constant resistance

A

the resistance doesn’t change with the current so at a constant temp current flowing through an ohmic conductor is directly proportional to the potential difference across it

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33
Q

What position must Ammeters be in to measure amps

A

Series

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34
Q

What position must voltmeters be in to measure Potential difference

A

Parallel

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35
Q

What are light dependent resistors

A

a resistor that dependent on the intensity of the light
in darkness resistance is highest
in bright light resistance falls

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36
Q

What are Thermistors

A

a temperature dependent resistor

in hot conditions the resistance falls

in cool conditions resistance increases

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37
Q

What are the qualities of a series circuit

A

the different components are connected in a line end to end
if one thing is disconnected the whole circuit fails
if all cells in a series circuit are connected and are the same way their potential difference adds up
Resistance adds up
current is the same everywhere

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38
Q

What happens to the total potential difference in a series circuit

A

the total potential difference is shared between all components in circuit

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39
Q

What happens to the potential difference of two cells when they are connected in the same direction in series

A

the potential difference is added up

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40
Q

In series circuits how do you get the total resistance

A

you add the resistances of all the components in the series circuit

41
Q

What happens when you add resistors in series

A

it increases the resistance of the circuit

42
Q

What happens when you add resistors in parallel

A

total current of circuit increases while total resistance decreases

43
Q

What is the relationship between current resistance and voltage

A

As long as resistance stays constant and voltage increases current should increase proportionally

44
Q

Why do filament lamps graphs look like that

A

as wire heats up it produces light.
When wire gets hotter there is more resistance. When there is more resistance there is less steep of a curve

45
Q

Why are diodes able to cause current to flow in only one direction

A

diode- device that only allows current to flow in one direction- does this by having high resistance in opposite direction

46
Q

What are diodes

A

devices that cause current to flow in one direction

47
Q

What is the function of a circuit breaker

A

breaks if to much current flows through a circuit

48
Q

What is the function of a diode

A

only allows current to flow in one direction

49
Q

What is the function of a light emitting diode

A

emits light if current flows through it in a certain direction

50
Q

What is the function of a fixed resistor

A

to provide a fixed amount of resistance in ohms

51
Q

What is the function of a variable resistor

A

to provide an easily changeable resistance

52
Q

What is a light dependent resistor

A

a resistor where resistance decreases when light intensity increases

53
Q

What is the function of a thermistor

A

as the temperature increases the resistance decreases

54
Q

How much energy does a power station produce

A

The amount of energy a power station produces is based on demand so it varies

55
Q

When does energy demand peak

A

Late afternoon or evening

56
Q

How do power stations deal with surges in demand for electricity

A

Power stations deal with surges in demand by working well under maximum capacity as they need to have spare capacity when dealing with surges

57
Q

What happens when lots of current is transmitted through a wire

A

Most of the energy is wasted and transmitted to the surroundings through heat

58
Q

How does the national grid minimalize energy loss

A

It transmits low amounts of current with high voltage

59
Q

What is the role of step up transformers in the national grid

A

They increase the voltage to around 400000 volts while also decreasing the current

60
Q

What is the role of pylons in the national grid

A

Supports the electrical cables that transmit the current and voltage

61
Q

What is the role of wires in the national grid

A

wires transmit current in the national grid

62
Q

What is the role of step down transformers in the national grid

A

They reduce the voltage back down to 230 volts and increase the current

63
Q

Why is it important to reduce voltage before it reaches towns and cities

A

High voltage is dangerous
Will blow appliances apart

64
Q

What is the UK main supply Hz

A

50

65
Q

What is Hz

A

how many times the ac current fluctuates between positive and negative a second

66
Q

Where do we find D.C. current

A

in cells and batteries

67
Q

What is the function of Oscilloscopes

A

They create P.D time graphs

68
Q

What is a common problem that happens in a circuit

A

Sudden increases in current (surges)

69
Q

When do surges usually happen

A

When you turn your appliance on or off or there is a fault in the circuit or appliance

70
Q

What problems do surges create

A

Can damage appliances
cause fires
cause electric shocks

71
Q

What are some safety precautions of surges

A

Fuses
Earth wires
Double insulation
Circuit breakers

72
Q

How do fuses and circuit breakers stop surges

A

They break the circuit whenever the current gets too high

73
Q

What is a fuse

A

A thin piece of wire that is connected to the live wire

74
Q

How does a fuse break a circuit

A

When a surge goes through the live wire it will go through the fuse
the fuse will melt due to the surge thus breaking the circuit

75
Q

Adv of fuse

A

They are simple
They are cheap

76
Q

Disadv of Fuses

A

Permanently broken after single surge

77
Q

How do Circuit breakers break a circuit

A

When a surge goes through the circuit breaker the circuit breaker gets tripped thus turning off the entire circuit

78
Q

Adv of Circuit breakers

A

Circuit breakers are not broken after single use

79
Q

Disadv of circuit breakers

A

They are more expensive than fuses

80
Q

How does Earthing stop electric shocks

A

Earth wire diverts current and gives it an alternative pathway instead of going through casing

81
Q

How does double insulating stop electric shocks

A

if you cover the device in a non-conductive material the current wont go into the casing and give you an electric shock.
You then wont normally need an earth wire

82
Q

What are the risks of using radiation

A

Ionising radiation- ionise atoms in living cells- may damage them (leads to cancer) or kill them off completely

83
Q

What is exposure to radiation called

A

Irradiation

84
Q

How are alpha sources of radiation dangerous in the body

A

Inside the body, alpha sources can cause damage in a localised area, so contamination is the main concern when working with alpha source

85
Q

What is contamination

A

When unwanted radioactive atoms get on or into an object

86
Q

Why is contamination dangerous

A

If the radioactive atoms get into the body they can then decay releasing radiation harming the body

87
Q

Why are beta and gamma sources less damaging inside the body

A

they are more likely to pass through a cell than to be absorbed

88
Q

Why are Gamma sources the least dangerous inside the body

A

They mostly pass straight out of the body as they have the lowest ionising power

89
Q

Why are beta and gamma sources dangerous outside the body

A

The beta and gamma sources can penetrate the body and get into the vital organs

90
Q

Why are alpha particles less dangerous outside the body

A

Alpha particles can’t penetrate the skin and are easily blocked by a small air gap

91
Q

What is half-life

A

The time taken for the number of radioactive nuclei in an isotope to halve

92
Q

How many protons and neutrons is an alpha particle made out of

A

An alpha particle is made of 2 protons and 2 neutrons

93
Q

How are nuclear equations written out

A

Atom before decay —-》atom after decay + radiation emitted

94
Q

What happens in an atom when beta decay occurs

A

A neutron in the nucleus turns into a proton while a fast-moving electron (beta particle) is released

95
Q

What happens to the atomic mass when beta decay occurs

A

The atomic mass doesn’t change as a proton and a neutron have the same value of mass

96
Q

What happens to the charge of the atom when beta decay occurs

A

Since the protons in the nucleus have increased by 1, the charge of the atom will also positively increase

97
Q

What happens to the atomic number of the atom when beta decay occurs

A

Since the atomic number is dependent on the number of protons, the atomic number will increase as during beta decay, the number of protons increase

98
Q

How can the distance at which electrons orbit the nucleus change

A

If electrons absorb EM radiation, they move to a higher energy level, which is further away from the nucleus

If they release EM radiation, they move to a lower energy level that is closer to the nucleoside

Revision (18 decks)

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