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5PHD (Class of '21) > IGCSE Physics > Flashcards

IGCSE Physics Flashcards

1
Q

What happens when current flows through a resistor

A

When current flows through a resistor it heats up (this effect is used in kettles and toasters etc.)

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2
Q

Name some electrical conductors (low resistance, allow current to easily flow)

A

Metal, graphite

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3
Q

charge, current and time

A

charge = current x time

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4
Q

What materials does conduction happen best in and why?

A

Solids; particles are close together so can pass energy quickly. Works best of all in metals due to free electrons.

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5
Q

What is another name for the rate of flow of charge?

A

Current

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6
Q

Charge, Q

A

coulomb (C)

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7
Q

What is the nature of an electric current in a metal conductor?

A

A flow of negatively charged electrons flowing from the negative side of a battery or power supply

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8
Q

Electric current, I

A

amp (A)

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9
Q

Name some electrical insulators (high resistance, do not allow current to flow)

A

Plastic, wood, (pure) water

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10
Q

What experiment can be done to demonstrate charging by friction?

A

Rub a plastic rod with a cloth, show charge on coulombmeter or repel/attract other charged things.

Rub a balloon on jumper / hair stick to wall.

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11
Q

How can electrostatic charge cause a fire at a petrol station.

A

Charge builds up on car while driving

a spark when person touches car

+ fuel vapour = explosion

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12
Q

Give some useful uses of electrostatic charges

A

Paint spraying,

Chimney precipitator (smoke cleaner),

Photocopier,

Ink Jet Printer

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13
Q

How does a material gain a negative electrostatic charge?

A

Object gains electrons to gain a negative charge

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14
Q

How can fires be prevented when refuelling aircraft (linked to electrostatic charge)

A

Attach Earthing strap (to discharge aircraft) before beginning to refuel

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15
Q

How does a material gain a positive electrostatic charge?

A

Object loses electrons to gain a positive charge

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16
Q

What are the benefits of using electrostatically charged spray paint

A

Paint has same charge so repels = fine mist, no clumps.

Object has opposite charge, attracts paint into corners and around the back

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17
Q

When two objects with a positive electrostatic charge are close together they?

A

Repel as like charges repel

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18
Q

How can electrostatic charge be used to clean smoke in a chimney?

A

Smoke particles charged by wires and attracted to charged plates

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19
Q

What component is this?

A

Variable resistor

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20
Q

How does a fuse work

A

When the current goes higher than the value of the fuse it melts. This breaks the circuit and stops current flowing

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21
Q

What happens to the resistance of a thermistor as it is heated

A

High temperatures reduces the resistance of a thermistor

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22
Q

Give an example of an AC source and a DC source

A

Mains are an AC source. Batteries are DC sources

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23
Q

voltage, current and resistance

A

voltage = current x resistance

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24
Q

What component is this?

A

Bulb

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25
Q

What happens to the current in a circuit when the resistance is decreased?

A

Current increases as resistance decreases

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26
Q

What happens to the current in series circuit as more bulbs are added?

A

More bulbs in series increases the resistance and decreases the current

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27
Q

Resistance, R

A

ohm ( )

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28
Q

What component is this?

A

Diode

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29
Q

What happens to the resistance of an LDR as more light is shone on it?

A

Bright light reduces the resistance of an LDR

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30
Q

What component is this?

A

Wire

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31
Q

What is double insulation

A

Appliances with plastic cases are double insulated; even if live wire comes loose inside, a user can’t be shocked

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32
Q

Explain parallel circuits

A

Several routes for current to take, allows components to be switched on individually (e.g. lights at home), components get full supply voltage

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33
Q

What component is this?

A

Thermistor

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34
Q

How can you show current is flowing in a circuit

A

A bulb or LED will light when a current flows. Or use an ammeter (in series)

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35
Q

What are meters X and Y?

A

X is a voltmeter (in parallel)

Y is an ammeter (in series)

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36
Q

What component is this?

A

LDR (light dependent resistor)

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37
Q

What is the difference between Alternating Current (AC) and Direct Current (DC)

A

DC (direct current) only flows in one direction. AC (alternating current) constantly changes direction.

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38
Q

Potential Difference, V

A

volt (V)

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39
Q

Explain series circuits

A

Only one loop, simple, if one component fails no current flows

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40
Q

What component is this?

A

Diode

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41
Q

Only appliances with what sort of case need an Earth wire?

A

Appliances with metal cases; if the live wire comes loose someone could get a shock without an Earth wire.

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42
Q

Energy transferred per unit charge is known as?

A

Voltage

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43
Q

One volt is equal to one?..

A

One joule per coulomb

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44
Q

How does an Earth wire prevent electric shock

A

Large current flows to the Earth and blows fuse, breaking the circuit

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45
Q

What happens to a wire when current flows through it

A

Wire heats up

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46
Q

What appliances use the hearing effect of current?

A

Kettle, toaster, electric grill, electric heater

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47
Q

Why does a flowing current increase the temperature of a wire?

A

Electrons collide with lattice and transfer energy

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48
Q

Power, current, voltage?

A

power = current x voltage

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49
Q

What component has this I-V graph?

A

wire or resistor

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50
Q

What component has this I-V graph?

A

bulb

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51
Q

What component has this I-V graph?

A

diode

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52
Q

Describe how the current changes with voltage in wires/resistors

A

they are directly proportional (as long as temperature doesn’t change)

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53
Q

Describe how the current changes with voltage in bulbs

A

non-linear

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54
Q

Describe how the current changes with voltage in diodes

A

non-linear

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55
Q

Why is current conserved at a junction?

A

Electrons aren’t used up. Number of electrons entering a junction per second is the same as the number leaving per second.

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56
Q

If two componenets are connected in parallel what is the voltage across each one?

A

The same

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57
Q

If two componenets are connected in series what is the voltage across them

A

It depends on their resistances

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58
Q

In a series circuit is the supply voltage split across components?

A

Yes; voltage splits across components based on their resistances

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59
Q

In a parallel circuit is the supply voltage split across components?

A

No; voltage is the same across componenets

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60
Q

In a series circuit is the current the same everywhere?

A

Yes; current is the same everywhere

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61
Q

In a parallel circuit is the current the same everywhere?

A

No; current splits at junctions

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62
Q

energy transferred, charge, voltage

A

energy transferred = voltage x charge

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63
Q

What equation links pressure difference, height, density and g

A

pressure difference = height x density x g

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64
Q

What equation links density, mass and volume

A

density = mass / volume

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65
Q

When a gas or liquid is at rest, what can you say about the pressure?

A

at a given depth, pressure in a fluid at rest acts equally in all directions

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66
Q

How would you find the volume of a small irregular object (e.g. a pebble)

A

submerge in water. The volume of water displaced = volume of pebble

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67
Q

How would you find the volume of a regular object (e.g. a cube of metal)

A

measure each side (with ruler) and multiply together

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68
Q

What happens to the pressure acting in a fluid as you go deeper?

A

pressure increases as you go deeper into a fluid

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69
Q

What equation links pressure, force and area

A

pressure = force / area

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70
Q

How is electricity generated in a generator?

A

A large coil is spun in a strong magentic field, this causes a force on the electrons and makes them flow producing a current.

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71
Q

How can you increase the amount of voltage which is induced when moving a magnet into a coil?

A

Stronger magnet, move magnet faster

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72
Q

When a wire is moved through a magnetic field what happens?

A

A wire moving through a magnet causes a current to flow

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73
Q

What are circuit breakers

A

Circuit breakers break the circuit when the current goes higher than a certain value. Unlike fuses, they can be reset once tripped.

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74
Q

How can you increase the speed of a motor (or volume of a speaker)?

A

Stronger magnet, more current

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75
Q

How can you produce more electricity in a generator?

A

Stronger magnet, spin coil faster

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76
Q

What do the thumb and fingers represent when using Flemming’s Left Hand Rule?

A

thumb = force (direction of movement),

First Finger = Field,

seCond finger = Current

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77
Q

What is felt when a current-carrying wire is in a magnetic field?

A

A force is felt when a wire carries a current in a magnetic field

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78
Q

What is produced around a conductor when electrical current flows?

A

An electromagentic field is created when current flows

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79
Q

A charged partical experience no force due to a magnetic field when?

A

Moving parallel to field

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80
Q

What force is felt by the charged particle

A

No force felt as particle is moving parallel to field.

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81
Q

How are electromagnets made?

A

A coil of wire around an iron core

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82
Q

Describe how thermal energy is transferred by conduction

A

Particles knock into each other and pass on the energy

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83
Q

Describe how thermal energy is transferred by convection

A

Hotter regions of fluid expand, become less dense and float on colder regions

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84
Q

Describe how thermal energy is transferred by radiation

A

Thermal radiation is an electromagnetic wave.

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85
Q

How can you prevent heat transfer by conduction?

A

Use insulators (such as air)

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86
Q

How can you prevent heat transfer by convection?

A

Trap the fluids (e.g. trapping air in wool). This prevents both conduction and convection.

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87
Q

How can you prevent heat transfer by radiation?

A

Shiny surfaces are poor emitters. They also refelect the thermal radiation back.

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88
Q

How do radiators in your house heat a room (hint, not by radiation)

A

Radiators heat air which rises and produces a convection current. Cold air is drawn into the bottom of the radiator too.

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89
Q

How does convection produce wind?

A

Air is heated, expands, becomes less dense, rises, colder air rushes into the area of low pressure.

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90
Q

What are the advantages of fossil fuels?

A

Reliable (not weather dependent),

already established,

high power output

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91
Q

What are the advantages of geothermal power?

A

Renewable,

no air pollution,

low running costs, no fuel costs

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92
Q

What are the advantages of hydroelectric power?

A

Renewable,

no air pollution,

low running costs, no fuel costs

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93
Q

What are the advantages of nuclear power?

A

Reliable (not weather dependent),

already established,

high power output

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94
Q

What are the advantages of solar cells?

A

Renewable,

no air pollution,

low running costs, no fuel costs

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95
Q

What are the advantages of solar heating systems?

A

Renewable,

no air pollution,

low running costs, no fuel costs

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96
Q

What are the advantages of wind power?

A

Renewable,

no air pollution,

low running costs, no fuel costs

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97
Q

What are the disadvantages of fossil fuels?

A

Release CO2 and air pollution, mining hazardous

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98
Q

What are the disadvantages of geothermal power?

A

Only works in very specific places,

deep drilling difficult and expensive

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99
Q

What are the disadvantages of hydroelectric power?

A

Floods a large area,

disrupts people and animals

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100
Q

What are the disadvantages of nuclear power?

A

Produces long lasting radioactive waste which must be securely stored,

mining hazardous

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101
Q

What are the disadvantages of solar cells?

A

Unreliable (doesn’t work at night or when cloudy),

large area needed to replace a typical power station,

inefficient

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102
Q

What are the disadvantages of solar heating systems?

A

Unreliable (doesn’t work at night),

may need additional boiler to produce hot water

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103
Q

What are the disadvantages of wind power?

A

Unreliable (only works when windy),

needs lots of land,

visual pollution, a large number needed to replace a typical power station

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104
Q

What are the general advantages of renewable sources of power?

A

Renewable,

no air pollution,

low running costs, no fuel costs

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105
Q

What are the general disadvantages of renewable sources of power?

A

Unreliable (weather dependent),

large amount of land needed to replace a typical power station

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106
Q

What is the efficiency of this machine

A

useful output energy = 10J

total input energy = 100J

efficiency = 10/100

= 0.1 or 10%

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107
Q

What is the principle of conservation of energy

A

Energy cannot be created or destroyed; only changed from one form to another.

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108
Q

What materials does convection happen best in and why

A

Fluids (gases and liquids); particles must be free to move so can’t happen in a solid

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109
Q

What materials does radiation happen best in and why?

A

Transparent (see through) materials; thermal radiation can be absorbed by some materials and pass through others.

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110
Q

Why aren’t machines 100% efficient?

A

Typically some energy is lost to the surroundings as heat.

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111
Q

Energy, E

A

joule (J)

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112
Q

List the 8 energy stores

A

chemical, electrical, kinetic, gravitational, elastic, thermal, magnetic, electrostatic, nuclear

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113
Q

List the 4 energy transfers

A

mechanically, electrically, by heating, by radiation (light and sound)

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114
Q

When will an object emit thermal radiation?

A

When it is hotter than its surroundings

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115
Q

When will an object absorb thermal radiation?

A

When it is hotter than its surroundings

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116
Q

What surface is the best absorbers of thermal radiation?

A

Matt Black

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117
Q

What surface is the best emitters of thermal radiation?

A

Matt Black

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118
Q

What surface is the worst absorbers of thermal radiation?

A

Shiny Silver

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119
Q

What surface is the worst emitter of radiation?

A

Shiny Silver

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4
5
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120
Q

Forces can do what to an object?

A

Change speed, shape or direction

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121
Q

weight, mass and gravitational field strength

A

weight = mass x gravitational field strength

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122
Q

Force, F

A

newton (N)

123
Q

What is the force which opposes motion

A

Friction (e.g. against a road) or drag (e.g. moving through air)

124
Q

force, mass and acceleration

A

force = mass x acceleration

125
Q

What is the difference between scalar and vector quantities?

A

Vectors have a direction as well as a magnitude (size)

126
Q

Name some vector quantities

A

Velocity,

displacement,

acceleration,

force,

momentum,

moment,

current

127
Q

Name some scalar quantities

A

Speed,

mass,

volume,

time,

energy,

charge,

pressure,

power

128
Q

Where does an objects weight always act

A

Through its centre of gravity

129
Q

Factors which affect thinking distance

A

Speed, awareness (tired, alcohol)

130
Q

What makes something an elastic material

A

Material regains original shape once stretching force is removed

131
Q

Moment

A

newton metre (Nm)

132
Q

What is the relationship between force and extension for a spring

A

Force is directly proportional to extention (if force doubles extension doubles)

133
Q

What happens to the speed of an object as it falls?

What happens to its drag?

A

Speed increases (resultant force downwards)

drag increases

134
Q

Factors which affect braking distance

A

Speed, weight of vehicle, quality of brakes and tryes, road surface

135
Q

moment, force and perpendicular distance from pivot

A

moment = force x perpendicular distance from pivot

136
Q

Why does an object reach terminal velocity?

A

As the speed and drag increase, eventually weight = drag so no resultant force

137
Q

Which support provides more force? Why?

A

Moments about the person are equal.

A closer to person, so needs bigger force to provide same moment as B.

138
Q

The initial linear part of a force-extension graph is linked to what law?

A

Hooke’s Law (Force is directly proportional to extension)

139
Q

How can you gain accurate results when investigating force and extension of a helical spring

A

Take eye level readings, keep ruler vertical and close to spring

140
Q

How do you calculate stopping distance?

A

Stopping distance = Thinking distance + Braking distance

141
Q

Force, mass, acceleration

A

force = mass x acceleration

142
Q

Weight, mass, gravitational field strength

A

weight = mass x g

143
Q

What force is needed in the equation F = ma?

A

Resultant or overall force.

144
Q

Which direction does friction always act?

A

In the opposite direction to motion

145
Q

What’s wrong with -50K as a temperature?

A

You can’t have negative kelvin temperatures, absolute zero (0K) is the coldest temperature possible

146
Q

How do gas particles exert pressure on a container

A

molecules collide with walls of container,

exert a force,

over a given area,

pressure = force / area

147
Q

Temperature, T

A

kelvin (K)

148
Q

How do you convert from K to C?

What is 300K in C?

What is 100K in C?

A

Subtract 273,

300K-273 = 27 C,

100K-273 = -173 C

149
Q

How do you convert from C to K?

What is 20 C in K?

What is -40 C in K?

A

Add 273,

20 C + 273 = 293 K,

-40 C + 273 = 233 K

150
Q

When investigating the relationship between pressure and volume what two quatities must you keep constant?

A

Temperature and mass of gas must be kept constant when investigating pressure and volume

151
Q

What happens to the pressure of a gas in a sealed container when you heat it? Why?

A

Pressure increases when you heat a sealed container of gas,

molecules move faster hitting walls harder and more often,

more force exerted on same area,

pressure increases

152
Q

How can air molecules move heavy smoke particles (Brownian motion)

A

lots of tiny, fast moving air molecules exert enough force on a smoke particle to change its direction

153
Q

What happens to particles at absolute zero? What is the pressure? Why?

A

Paricles stop moving at absolute zero (no KE), pressure is zero as particles are not colliding with walls

154
Q

What happens to the average speed of gas molecules as you heat a gas?

A

Average speed of gas molecules increases as you heat a gas

155
Q

If you double the volume of a sealed container of gas (at a constant temperature) what happens to the presure?

A

Pressure will halve

156
Q

If the kelvin temperature of a gas doubles, what happens to the pressure it exerts?

A

Pressure doubles too

157
Q

What is the relationship between kelvin temperature of a gas and average kinetic energy its molecules?

A

Kelvin temperature is directly proportional to average kinetic energy.

Doubling the temperature (in kelvin!) doubles KE

158
Q

When a magnet moves through a coil of wire what happens?

A

A magnet moving through a coil causes a current to flow

159
Q

What is the relationship between input and output power of a transformer?

A

Pprimary = Psecondary

IpVp = IsVs

160
Q

Why is iron used as the core for a transformer?

A

Soft magnetic material; gains and loses magnetism easily.

161
Q

Why is the iron core in a transformer laminated?

A

Prevents eddy currents;

stops heating;

keeps efficiency high.

162
Q

What sort of electricity is needed to make transformers work?

A

AC; current must change direction so magnetic field keeps changing direction

163
Q

More turns on the secondary coil is what sort of transformer?

A

Step up; voltage is bigger across the secondary coil

164
Q

Why are step up and step down transformers used in the National Grid?

A

Voltage stepped up (e.g 100x);

Current drops by the same amount (100x lower);

less power loss due to heating;

Stepped down to be safe in homes.

165
Q

Why doesn’t DC work for transformers?

A

DC doesn’t change direction so the magnetic field is constant

166
Q

More turns on the primary coil what sort of transformer?

A

Step down; voltage is bigger across the primary coil

167
Q

Why is a current induced in the secondary coil?

A

The secondary coil sees a changing magnetic field;

electrons experience a force and move;

which induces a current

168
Q

Describe the structure of a transformer

A

Two coils of wire wrapped around a laminated iron core

169
Q

Why is the image in a mirror virtual?

A

The image in a mirror can’t be projected onto a screen

170
Q

When a wave is refracted what two things change

A

Speed and direction change during refraction

171
Q

When the angle of incidence is greater than the critical angle light is

A

Totally internally reflected

172
Q

Which way does light bend when it enters a material with a higher refractive index (e.g. air to glass)

A

Light bends towards the normal when it goes from air to glass

173
Q

refractive index and critical angle

A

n = 1 / sin c

refractive index = 1 / sin (critical angle)

174
Q

When the angle of incidence is less than the critical angle light is

A

When the angle is less than the critical angle, light is refracted

175
Q

refractive index, angle of incidence, angle or refraction

A

n = sin i / sin r

refractive index = sin (angle of incidence) / sin (angle of refraction)

176
Q

What is the frequency range for human hearing

A

20 Hz - 20 000 Hz

177
Q

What is the critical angle

A

When ligh hits the boundary at the critical angle the angle of refraction is 90

178
Q

What is the law of reflection?

A

Angle of incidence = Angle of reflection

179
Q

The frequency of a sound wave is linked to its?.

A

pitch

180
Q

The amlitude of a sound wave is linked to its?.

A

volume

181
Q

How can you find the frequency of a sound wave from an oscilloscope trace

A

Measure time period T (of one wave)

Use f = 1/T (careful with milli seconds)

e.g T = 3ms

so f = 1/0.003 = 333Hz

182
Q

What two pieces of equipment are needed to display a sound wave?

A

Microphone and oscilloscope

183
Q

Give some uses for total internal refelction

A

Fibre optic cables, reflectors, binoculors

184
Q

The loundness of a sound wave is linked to its?

A

Amplitude

185
Q

What is a magnetic field line?

A

A magnetic field line shows the direction of a magnetic field (N to S). Where lines are close together the field is strong.

186
Q

How would you describe a uniform field (3 marks)

A

Field lines are straight, parallel and equally spaced in a uniform field

187
Q

How can you visualise the shape of a magnetic field (3 marks)

A

Place magnet under paper, sprinkle iron filings on top of paper, gently tap paper so filings line up with field lines.

188
Q

How can you produce a uniform magnetic field (3 marks)

A

Place two attracting bar magnet poles (N&S) close together, hold them in place to avoid them touching

189
Q

How can you see the shape and direction of a magnetic field

A

Use plotting compasses

190
Q

Magnets can attract?

A

Magnetic materials (and other magnets too)

191
Q

Magnets can attract or repel?

A

Other magnets

192
Q

What has the following magnetic field shape?

A

Field around a current carrying wire

193
Q

What has the following magnetic field shape?

A

Field around a flat coil

(looks like an owl)

194
Q

Magnetically hard materials….

A

Are difficult to magnetise but keep their magnetism

195
Q

Magnetically soft materials…

A

Are easy to magnetise but lose their magnetism quickly

196
Q

What has the following magnetic field shape?

A

Field around a solenoid (same shape as a bar magnet)

197
Q

How can magnetism be induced in a magnetic material?

A

Placing a magnet close to a magnetic material will induce magnetism in the magnetic material

198
Q

What is conservation of momentum?

A

Momentum before a collision (or explosion) is equal to the momentum after.

Assuming no external forces act.

199
Q

How does bending you knees help prevent injury?

A

Increases collision time,

lower deceleration (a=V/t),

lower force (F=ma)

200
Q

What is Newton’s third law?

A

If object A exerts a force on object B, object B exerts an equal and opposite force on object A

201
Q

How does a stretching seatbelt reduce injury

A

Increases collision time,

lower deceleration (a=V/t),

lower force (F=ma)

202
Q

What equation links momentum, mass and velocity?

A

Momentum = mass x velocity

203
Q

The gradient of a velocity-time graph gives

A

Acceleration

204
Q

The area under a velocity-time graph gives

A

Distance travelled

205
Q

average speed, distance and time

A

speed = distance / time

average speed = total distance / total time

206
Q

?霘The gradient of a distance-time graph gives

A

Speed

207
Q

acceleration, change in velocity and time taken

A

acceleration = change in velocity / time taken

208
Q

Time, t

A

second (s)

209
Q

Velocity (initial, final), (u,v)

A

metre per second (m/s)

210
Q

Acceleration, a

A

metre per second squared (m/s/s, m/s2)

211
Q

How many alpha-particles take this path?

What does this show?

A

Some of the particles take this path.

It shows there is a charged region

212
Q

What type of radioactive decay is most penetrating?

A

Gamma

213
Q

What are the artificial sources of background radiation?

A

Medical sources, fallout from nuclear weapons testing and use, nuclear accidents

214
Q

What are the dangers of ionising radiation?

A

Mutation and damage to cells and tissues

215
Q

After two half-lives, how much of an original sample is left?

A

One quarter

216
Q

What type of radioactive decay is most ionising?

A

Alpha

217
Q

In what two ways can radioactive decay be detected?

A

By photographic film and by a Geiger-M/泓ler (GM) Tube

218
Q

What isotope Carbon-14 often used for

A

radiometric dating; identifying how old something is based on the count rate of the carbon-14

219
Q

After three half-lives, how much of an original sample is left?

A

One eighth

220
Q

After four half-lives, how much of an original sample is left?

A

One sixteenth

221
Q

How many alpha-particles take this path?

What does this show?

A

Very few alpha particles take this path.

It shows there is a central positivley charged region which is very tiny and very dense.

222
Q

What are the natural sources of background radiation?

A

Radon gas, cosmic rays, the ground, food and drink

223
Q

What is the role of the control rods in a nuclear reactor?

A

To control the rate of reaction by absorbing neutrons

224
Q

What type of radioactive decay emits a helium nucleus?

A

Alpha

225
Q

What types of radioactive decay do not change an isotope’s mass number?

A

Beta and Gamma

226
Q

Give a danger and use for gamma

A

Danger = cancer, mutation,

Use = sterilising food and medical equipment

227
Q

What particle was fired at gold foil during Rutherford’s experiments. What charge did it have?

A

Alpha particle which has a positive charge

228
Q

What type of radioactive decay emits an electron?

A

Beta

229
Q

What is the role of the moderator in a nuclear reactor?

A

To slow neutrons down so that they can cause new fissions

230
Q

What type of radioactive decay changes both an isotope’s mass number and its atomic number?

A

Alpha

231
Q

What type of radioactive decay does not emit a particle?

A

Gamma

232
Q

What is the mass number?

A

The total number of protons and neutrons

233
Q

How many alpha-particles take this path?

What does this show?

A

Most alpha particles take this path.

It shows most of the atom is empty space

234
Q

Do isotopes have the same atomic number, or the same mass number?

A

Atomic number (number of protons)

235
Q

What type of radioactive decay can be stopped by a sheet of paper?

A

Alpha

236
Q

What is the atomic number?

A

The number of protons

237
Q

What type of radioactive decay can only be stopped by a few millimetres of aluminium?

A

Beta

238
Q

Radioactive activity, A

A

becquerel (Bq)

239
Q

What type of radioactive decay can only be stopped by a few centimetres of lead?

A

Gamma

240
Q

What particle do control rods absorb?

A

Neutrons

241
Q

What type of radioactive decay can be stopped by a few centimetres of air?

A

Alpha

242
Q

Describe the motion of gas particles

A

gas particles move in a random fast motion

243
Q

Describe the arrangement and motion of particles in a gas

A

No pattern;

Able to move freely/fast;

Larger space between particles;

244
Q

Describe the arrangement and motion of particles in a liquid

A

Irregular pattern;

Able to move over/past other particles;

Little space between particles;

245
Q

What change of state happens during condensing?

A

gas to liquid

246
Q

What change of state happens during melting?

A

solid to liquid

247
Q

What change of state happens during boiling?

A

liquid to gas

248
Q

What change of state happens during freezing?

A

liquid to solid

249
Q

Describe the arrangement and motion of particles in a solid

A

Regular pattern OR close packed;

Vibration in position;

Little space between particles

250
Q

Comets orbit what? What shapes are their orbits?

A

Comets orbit stars (e.g. the Sun) in elliptical orbits

251
Q

Our local galaxy is called

A

The Milky Way

252
Q

Natural satellites (e.g. moons) and artificial satellites (e.g. Hubble) orbit what?

A

Planets

253
Q

A galaxy is made up of

A

Billions of stars

254
Q

Why do different planets have different values of g (gravitational field strength)

A

Planets with more mass (e.g. Jupiter) have a higher value of g

255
Q

The universe is made up of .

A

Billions of galaxies

256
Q

Planets orbit what? What shape are their orbits?

A

Planets orbit stars (e.g. the Sun) in circular orbits

257
Q

Define amplitude

A

Amplitude is the maximum displacement above the equilibrium

258
Q

wave speed, frequency and wave length

A

wave speed = frequency x wave length

259
Q

What part of the EM spectrum has the longest wavelength

A

Radio has the longest wavelength

260
Q

Define the time period of a wave

A

Time period is how long it takes for a wave to pass a point

261
Q

Wavelength,

A

metre (m)

262
Q

Waves transfer without transferring .

A

Waves transfer energy and information without transferring matter

263
Q

Frequency, f

A

hertz (Hz)

264
Q

What is the easiest way to reduce risk of injury from microwaves, infra red, ultra violet or gamma

A

Avoid exposure

265
Q

Give a danger and use for microwaves

A

Danger = internal heating of body tissue,

Use = cooking and satellite communications

266
Q

Refraction is when a wave

A

…bends

267
Q

What is the order of the EM spectrum

A

Radio, Microwave, Infra-red, Visible, Ultra-violet, X-ray & Gamma

268
Q

Reflection is when a wave

A

…bounces off something

269
Q

Give a use for x-rays

A

looking at the insides of things (medical imaging and other objects)

270
Q

Give a danger and use for infra red

A

Danger = skin burns,

Use = cooking and night vision equipment

271
Q

Describe a transverse wave and give an example

A

Transverse waves travel at right angles to the oscillation which caused them. E.g. light, other EM waves, Mexican Waves

272
Q

What part of the EM spectrum has the highest frequency (and energy)

A

Gamma has the highest frequency

273
Q

Give a danger and use for ultra violet

A

Danger = blindness and damage to surface cells,

Use = flourescent lamps, security markings

274
Q

Give a use for visible light

A

Seeing, optical fibres, photography

275
Q

Define wavelength

A

Wavelength is the distance between two peaks or two troughs

276
Q

Describe a longitudinal wave and give an example

A

Longitudinal waves travel parallel to the oscillation which caused them. E.g. sound

277
Q

Give a use for radio

A

Communictions and broadcast

278
Q

Define frequency

A

Frequency is the number of waves going past a point per second

279
Q

What is the Doppler Effect?

A

A change in the observed frequency of an object moving towards or away from you.

280
Q

What happens to the observed frequency of a wave when its source is moving towards you?

A

Obsereved frequency increases

281
Q

What happens to the observed wave length of a wave when its source is moving towards you?

A

Obsereved frequency decreases

282
Q

What happens to the observed frequency of a wave when its source is moving away from you?

A

Observed wavelength decreases

283
Q

What happens to the observed wavelength of a wave when its source is moving away from you?

A

Observed wavelength increases

284
Q

Power, P

A

watt (W)

285
Q

What does work done = energy transferred mean?

A

If you do 10J of work on a system you transfer 10J of energy to it.

286
Q

The rate of doing work is also known as?

A

Power

287
Q

If a car has 20 000J of kinetic energy, how much work do the brakes have to do to stop the car?

A

20 000J

288
Q

efficiency, useful energy output and total energy input

A

efficiency = useful energy output / total energy input

(also efficiency = useful energy output / total energy output)

289
Q

gravitational potential energy, mass, g and height

A

gravitational potential energy = mass x g x height

290
Q

work done, force and distance moved

A

work done = force x distance moved

291
Q

If an object has 100J of gravitational potential energy when on a shelf and falls off, how much kinetic energy does it have just before hitting the floor? What have you assumed?

A

100J. But we assume there is no air resistance (100% efficient)

292
Q

One Watt is equal to what?

A

1 watt is 1 joule per second

293
Q

energy transferred and work done

A

energy transferred = work done

294
Q

kinetic energy, mass and speed

A

kinetic energy = 1/2 x mass x speed2

295
Q

List the 4 types of stored (potential) energies

A

Gravitational, Elastic, Nuclear, Chemical

296
Q

List the 5 types of non stored energies

A

Light, sound, thermal, kinetic, electrical

297
Q

What are the energy transfers involved with fossil fuels

A

chemical ?? thermal ?? kinetic ?? electrical

298
Q

What are the energy transfers involved with geothermal power

A

(nuclear) ?? thermal ?? kinetic ?? electric

299
Q

What are the energy transfers involved with nuclear power

A

nuclear ?? thermal ?? kinetic ?? electrical

300
Q

What are the energy transfers involved with solar cells

A

light ?? electrical

301
Q

What are the energy transfers involved with solar heating systems

A

thermal → themal

302
Q

What are the energy transfers involved with water power

A

gravitational ?? kinetic ?? electric

303
Q

What are the energy transfers involved with wind power

A

kinetic ?? electric

5PHD (Class of '21) (1 decks)

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