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Physics > Physics > Flashcards

Physics Flashcards

1
Q

Define conduction

A

transfer of thermal energy through a metal

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2
Q

How does the motion of gas particles changes when they are cooled?

A

slow down

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3
Q

Describe thermal conduction in a metal by electrons

A

electrons move freely throughout metal

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4
Q

Difference between boiling and evaporation (2)

A

boiling occurs throughout liquid

evaporation occurs at surface only

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5
Q

Technique to prevent energy loss from windows

A

double glazing - air between 2 panes of glass

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6
Q

Technique to prevent energy loss from floors

A

carpet

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7
Q

Technique to prevent energy loss from roof

A

loft insulation - insulation on top of ceiling prevents heat loss by conduction and convection

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8
Q

Technique to prevent energy loss from walls

A

cavity wall - 2 single walls separated by air prevents conduction

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9
Q

Does radiation need particles

A

no

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10
Q

Define boyle’s law

A

when temperature of gas stays constant, volume of gas inversely proportional to pressure

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11
Q

Define condensation

A

when substance changes from gas to liquid

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12
Q

Define boiling point

A

temperature which substance changes from liquid to gas

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13
Q

Define solidification

A

when substance changes from liquid to solid

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14
Q

Define melting point

A

temperature which it changes from solid to liquid

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15
Q

Factors that increase rate of evaporation (3)

A

higher temperatures

strong flow of air across surface

increased surface area

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16
Q

Define evaporation

A

when particles break away from liquid surface and form a gas/vapour

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17
Q

Define the brownian motion (2)

A

random motion of particles

large particles constantly hit by small fast particles

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18
Q

Motion of gas particles (2)

A

random + fast motion

collide with other particles/walls

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19
Q

Motion of liquid particles

A

slide over each other

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20
Q

Motion of solid particles

A

vibrate in place

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21
Q

Arrangement of gas particles (3)

A

irregular

widely spaced

particles able to move freely

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22
Q

Arrangement of liquid particles (3)

A

irregular

closely packed together

particles able to slide over each other

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23
Q

Arrangement of solid particles (3)

A

regular pattern

closely packed together

particles held in place

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24
Q

Properties of gases (4)

A

assumes shape of container

assumes volume of container

can be compressed

flows easily

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25
Q

Properties of liquid (3)

A

assumes shape of container

is not easily compressible

flows easily

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26
Q

Properties of solids (4)

A

fixed volume

fixed shape

not easily compressible

does not flow easily

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27
Q

The hotter an object is the more infra red they emit. True or False?

A

true

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28
Q

What do all objects emit

A

infra red radiation

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29
Q

Describe the convection cycle (5)

A

particles in area heated making fluid less dense

less dense liquid rises

particles’ KE converted GPE so temperature lost

as temperature lost particles need less space and become denser

cold particles fall to bottom

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30
Q

Why do metals conduct easier (2)

A

have free electrons

electrons can pass along metal allowing energy to transfer easily

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31
Q

Why are gases the worst conductors

A

their particles are far apart

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32
Q

Which state is the worst conductor of heat

A

gas

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33
Q

Why are solids the best conductors

A

their particles are close together

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34
Q

Which state is the best conductor of heat

A

solids

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35
Q

Define conduction (2)

A

method of heat transfer in solids, liquids, gas

transfers heat when vibrating particles bounce into each other

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36
Q

What increases the pressure of a gas (2)

A

increased temperature

decreased volume of sealed container

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37
Q

Why might a container implode (6)

A

Ambient temperature decrease inside

Kinetic energy of gas molecules decreases

Fewer collisions

Gas pressure decreases

gas pressure greater outside than inside

therefore big container implodes

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38
Q

What happens when work is done on a gas (2)

A

increases internal energy

increases temperature of gas

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39
Q

Why does an increase in temperature increase pressure (3)

A

increases kinetic energy of particles

average speed of molecules increased

will hit surface more often and with greater force

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40
Q

What does an increase in temperature do to pressure

A

increases pressure

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41
Q

How does a car tire keep inflated (3)

A

gas particles collide with tire walls

pressure created (force over area)

pressure inflates tire

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42
Q

Pressure formula

A

force/area

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43
Q

Define range

A

difference between hottest and coldest that can be measured

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44
Q

Define sensitivity

A

smallest change that can be measured

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45
Q

Define linearity

A

if liquid expands by same amount for each temperature increase

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46
Q

Explain contraction of gases (2)

A

contracts once cooled

particles move back to original positions

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47
Q

Explain expansion of gases (2)

A

easier to expand as gas particles far apart

distance between particles increase when heated

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48
Q

Why do liquids contract when cooled

A

particles move less

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49
Q

Why do liquids expand when heated

A

particles move more and need more space

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50
Q

What liquids expand and contract in thermometers (2)

A

mercury

alcohol

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51
Q

What happens when a solid is cooled

A

gets smaller/contracts

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52
Q

What happens when a solid is heated

A

gets bigger/expands

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53
Q

How does sweat help to cool us down (2)

A

energy taken when water molecules evaporate

cools skin

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54
Q

How evaporation works (4)

A

molecules move at different speeds

faster molecules in liquid escape liquid as gas

lowers average speed of remaining particles

cools substance down

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55
Q

What happens to atmospheric pressure as elevation above sea increases

A

decreases

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56
Q

What does an increase in energy cause for a system (2)

A

raises temperature

changes state

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57
Q

How does heating change the energy stored within a system

A

increases energy of particles

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58
Q

Define internal energy

A

energy stored in system

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59
Q

Are physical reactions easily reversible

A

yes

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60
Q

What is conserved when a substance changes state

A

mass

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61
Q

What increases as you go from solid to liquid (2)

A

volume

kinetic energy

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62
Q

Is nuclear energy renewable?

A

no

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63
Q

What energy do fossil fuels store

A

chemical energy

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64
Q

Examples of fossil fuels (3)

A

coal

oil

gas

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65
Q

Fossil fuels definition

A

carbon-based materials formed over millions of years from remains of plants and animals

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66
Q

cons of biomass energy

A

large area of land needed to grow trees

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67
Q

Pros of biomass energy (3)

A

doesn’t add to greenhouse effect

doesn’t need special equipment

renewable as long as we replace trees cut down

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68
Q

Biomass energy description (4)

A

chemical potential energy stored in live things can be converted to heat energy by burning them

trees absorb sun energy

Trees change energy into chemical energy

burning trees turns this energy into heat

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69
Q

Cons of wind energy (2)

A

only works if windy

can be ugly and noisy

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70
Q

Pros of wind energy (3)

A

renewable

no pollution as nothing is burned

quite cheap and easy to build

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71
Q

Cons of solar energy (2)

A

solar cells and panels are expensive

only works if sunny

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72
Q

Pros of solar energy (2)

A

renewable

no pollution as nothing gets burned

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73
Q

Application of solar energy (2)

A

energy from sun can be changed into electrical energy to power homes using solar cells

solar panels can use solar energy to heat water for homes

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74
Q

Solar energy description

A

earth gets heat and light energy from sun

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75
Q

Cons of tidal energy (2)

A

costs money to build dam

dam can cause local flooding

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76
Q

Pros of tidal energy (3)

A

renewable

cheap to run

reliable since there are always 2 tides every day

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77
Q

How does tidal energy work(3)

A

high tide has gravitational energy

at high tide water trapped behind dam

at ow tide water releases and generates electricity

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78
Q

Hydroelectric cons (3)

A

large area of land needed

damages wildlife habitats

dam can cause population displacement as it changes where water naturally flows

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79
Q

Hydroelectric pros (3)

A

renewable

no pollution - nothing gets burned

can store water and let water out when we need electricity

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80
Q

Cons of wave energy (3)

A

machines can be damaged by storm

require lots of machines to get reasonable amount of energy

machines cost a lot of money

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81
Q

Pros of wave energy (2)

A

renewable

no pollution as nothing gets burned

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82
Q

Description of Wave energy (2)

A

sea waves have kinetic energy

machines bob up and down in waves generating electricity

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83
Q

Disadvantages of geothermal (2)

A

few places in the world to do this

cost money to drill into ground

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84
Q

Benefits of geothermal (3)

A

renewable

no pollution as nothing gets burned

doesn’t damage environment

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85
Q

What is energy efficiency? (2)

A

measure of how well device transfers energy into form we want

proportion of input energy which device transforms into useful output energy

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86
Q

Can energy be created or destroyed?

A

no - only transferred

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87
Q

What is energy

A

ability to make something happen

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88
Q

Efficiency formula

A

(useful energy output/energy input) x 100

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89
Q

How does nuclear fission work

A

splitting nucleus releases stored energy

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90
Q

How does geothermal power work (3)

A

cold water pumped below ground

hot rocks heat water into steam

steam generates electricity

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91
Q

How does solar power work (2)

A

solar cells convert light energy to electrical energy

electric current charges battery that stores chemical potential energy

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92
Q

How does hydroelectric power work (4)

A

water flows through pipe to turbines

water turns turbine

turbine drives generator

generator produces electricity

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93
Q

How does wind power work (2)

A

kinetic energy of wind rotates blades

blades turn turbines that generate electricity

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94
Q

Define non-renewable

A

energy sources which cannot be replaced once used up

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95
Q

Power station steps (5)

A

fuel burned and steam produced in boiler

steam turns turbine

turbine drives generator

generator produces electricity

electricity supplied to homes, industry

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96
Q

Where do we obtain most of our energy

A

fossil fuels (coal, oil gas)

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97
Q

Measurment of power

A

watts (W)

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98
Q

Power formula

A

work done (Joules)/time taken (s)

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99
Q

Define power

A

the rate of doing work/transferring energy

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100
Q

What is the law of conservation of mass

A

energy cannot be created or destroyed

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101
Q

Define sound energy (2)

A

transfer small amount of energy from the source of the noise

sound vibrates air particles as a longitudinal wave

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102
Q

Define light energy

A

light waves transfer energy to the object the light strikes (absorbed by)

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103
Q

Define electrical energy

A

electrical currents transfer electricity to different places

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104
Q

Define thermal energy

A

heat energy contained within an object

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105
Q

Define nuclear energy

A

energy stored between strong bonds of nucleus

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106
Q

Define chemical potential energy (2)

A

energy stored in atomic forces/bonds

energy can be transferred by breaking the bonds

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107
Q

Define elastic potential energy

A

energy stored in stretched objects

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108
Q

Define kinetic energy

A

energy stored by a moving object

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109
Q

Define gravitational potential energy

A

energy stored by an object raised up in a gravitational field

110
Q

Formula for amount of kinetic energy stored

A

1/2 x mass (kg) x velocity^2 (m/s)

111
Q

Formula for gravitational potential energy

A

mass (kg) x acceleration due to gravity (10) x height above ground (m)

112
Q

Energy used to describe stored potential energy transferred to movement energy

A

kinetic energy

113
Q

When a load is raised above the ground what energy will it gain

A

gravitational potential energy

114
Q

When stretching or compressing a spring what energy will it have

A

elastic potential energy

115
Q

Define potential energy

A

stored or hidden energy

116
Q

When an object is lifted vertically, what does the amount of work done depend on? (2)

A

weight of the object

vertical distance it moves

117
Q

When an object is lifted vertically, what is the force moved?

A

the weight of the object

118
Q

Formula for work

A

work done = force x distance travelled in direction of force

119
Q

Unit of work

A

joules (J)

120
Q

What does the amount of work depend on (2)

A

magnitude of force
distance moved in the direction of force

121
Q

What is work (2)

A

energy transferred

application of force which results in movement

122
Q

Amplitude of sound wave

A

loudness of sound

123
Q

Frequency of sound wave

A

pitch of sound wave

124
Q

Range of human hearing

A

20Hz - 20,000 Hz

125
Q

Uses of microwaves (2)

A

radar

cooking

126
Q

Features of microwaves (2)

A

largest wavelengths

least amount of frequency/energy

127
Q

Dangers of UV rays (2)

A

can damage surface cells of body

can cause blindness or skin cancer

128
Q

Infrared radiation damage

A

can burn skin/body tissue

129
Q

Speed which all electromagnetic waves travel in a vacuum

A

3 x 10^8

130
Q

Features of infrared radiation (4)

A

emitted by all objects

hotter objects emit more than cold

3rd largest wavelength

4th greatest energy/frequency

131
Q

Features of ultraviolet rays (3)

A

component of sun rays

3rd shortest wavelength

3rd greatest energy/frequency

132
Q

Uses of X-rays (2)

A

treat cancer - destroy tumour cells

screen baggage/scan objects - different materials absorb different amounts of X-rays

133
Q

Features of X-rays (3)

A

second greatest energy/frequency

second shortest wavelength

produced when high-energy electrons fired at target

134
Q

Use of gamma rays (2)

A

radiotherapy - kill cancer cells

tracer - track substances in biological systems

135
Q

Features of gamma rays (3)

A

shortest wavelength

greatest frequency/energy

can cause cancer/mutation in cells

136
Q

Define a real image (5)

A

inverted

diminished

closer to lens than distance of object from lens

image where ray actually passes

can be picked up on suitable screen

137
Q

Define the focal length

A

distance between lens and principal focus

138
Q

Define the principal focus

A

point where parallel light rays all cross over

139
Q

Features of convex(converging) lenses

A

cause parallel light rays to converge to one point

140
Q

Define total internal reflection

A

at greater angles of incidence, rays entirely reflected back inside medium

141
Q

Refractive index formula critical angle

A

1/sin(critical angle)

142
Q

Define the critical angle

A

angle of incidence which angle of refraction becomes 90 degrees

143
Q

Speed of light in vacuum

A

3 x 10^8

144
Q

Refractive index of vacuu

A

1

145
Q

Refractive index formula (2)

A

sin(angle of incidence) / sin (angle of refraction)

speed of light in vacuum (air) / speed of light in material

146
Q

Define the refractive index

A

indicates
by how much a material changes direction of light

147
Q

Define the angle of refraction

A

angle between refracted light ray and normal to surface

148
Q

Define the angle of incidence

A

angle between incident light ray and normal to surface

149
Q

Refraction of light (4)

A

light waves slow down when travel into material

at angle to glass = rays bend toward normal

rays travel out material = speed increases, bend away from normal

material has parallel sides = light resumes original direction

150
Q

Formula for angles of incidence/reflection

A

angle of incidence = angle of reflection measured to a normal when mirror reflects light

151
Q

Define a virtual image (5)

A

upright

larger than object

further from lens than distance of object from lens

cannot be projected on screen

rays do not actually pass

152
Q

Define laterally inversion (2)

A

left and right exchanged

e.g in mirror

153
Q

Features of light (2)

A

does not need medium to travel through

transverse

154
Q

Define diffraction

A

when wavefronts change shape when they go through gap

155
Q

Explain refraction (3)

A

wave slows down –> wavefronts crowd together –> wavelength shortens

wave strikes boundary ay angle –> part of wave slows down or speed up first

wavefronts go closer together and changes direction

156
Q

Define refraction

A

wave enters new medium at angle = wavefronts change direction

157
Q

Wave speed measurment

A

m/s

158
Q

Formula for wave speed

A

frequency(Hz) x wavelength(m)

159
Q

Define transverse wave

A

vibrations are at right angles to direction of wave travel

160
Q

Amplitude of longitudinal wave

A

maximum displacement of medium’s vibration from undisturbed position

161
Q

Wavelength of longitudinal wave

A

distance between 2 consecutive points of maximum compression

162
Q

Example of longitudinal waves

A

sound

163
Q

Define compression

A

regions where wave is squashed together

164
Q

Define rarefaction

A

regions where wave is spread out

165
Q

Define longitudinal wave

A

vibrations in direction of wave travel

166
Q

Define wavefront

A

moving line that joins all points on crest

167
Q

Define amplitude (2)

A

height of half the crest/trough

maximum displacement of wave from undisturbed position

168
Q

Define frequency

A

number of complete waves that go past each second

169
Q

Define wavelength

A

distance between 2 adjacent peaks/troughs of wave

170
Q

Define pressure (3)

A

how spread out a force is

ratio of force to area

force(N)/area (m^2)

171
Q

Define stable equilibrium

A

object that is difficult to topple

172
Q

How to calculate centre of mass (5)

A

hang object

suspend mass from same place using thread

mark position of thread

repeat at different place

centre of mass where 2 lines meet

173
Q

When will an object fall

A

centre of mass outside pivot

174
Q

Define centre of mass

A

one point where body mass all concentrated

175
Q

Define the principle of moments (3)

A

if object not turning

sum of clockwise moments about pivot

= sum of anticlockwise moments about pivot

176
Q

Define the turning effect of a force (2)

A

moment of the force

force (N) x perpendicular distance from pivot (m)

177
Q

Define Newton’s 3rd law

A

forces always come in pairs

178
Q

Formula for force

A

mass (kg) x acceleration (m/s^2)

179
Q

What will happen to the object if the forces are balanced (2)

A

object will be stationary

object will move at constant speed

180
Q

Define newton’s first law of motion

A

resultant force required to change the way something is moving

181
Q

one form of friction

A

air resistance

182
Q

Define friction

A

force between 2 surfaces which impedes motion and causes heating

183
Q

Hooke’s law formula

A

force (N) = spring constant (n/m) x extension of spring (m)

184
Q

Define hooke’s law

A

as force of weight increases = extension will proportionally increase until a certain limit

185
Q

Define the limit of proportionality

A

point where extension no longer proportional to load

186
Q

Effects of a force (3)

A

change object size

change object motion

change object shape

187
Q

Define a force

A

push or pull

188
Q

Density formula

A

mass (kg) / volume (m^3)

189
Q

Earth gravitational field

A

10N/kg

190
Q

weight measurement

A

newtons

191
Q

Formula for weight

A

mass (kg) x gravitational field strength (N)

192
Q

Distance from speed time graph

A

area under curve

193
Q

graph for increasing acceleration

A

curved upwards exponential

194
Q

Graph for steady acceleration

A

linear upward

195
Q

Graph for steady speed

A

horizontal

196
Q

Graph for acceleration

A

curved exponential upward

197
Q

Graph for speed

A

linear upward sloping

198
Q

Formula for acceleration (m/s^2)

A

change in velocity (m/s) / time taken (s)

199
Q

Formula for speed (m/s)

A

distance (m)/time (s)

200
Q

Circuit symbol for variable resistor

A

rectangle with arrow through

201
Q

Circuit symbol for battery

A
  • |I—|I-
202
Q

Circuit symbol for fuse

A

rectangle with line through

203
Q

Circuit symbol for Cell

A
  • |I-
204
Q

Define a magnetic field (3)

A

region of space where their magnetism affects other objects

lines which move away from north pole to south

more concentrated field lines = stronger magnet

205
Q

How do some modern alloys become magnetised (2)

A

magnetic field applied to molten alloy at high temp.

alloy solidifies while in magnetic field

206
Q

How can a steel bar be magnetised (2)

A

stroking it with strong magnet

placing bar north and hammering it

207
Q

How can permanent magnets become magnetized using electricity

A

large direct current running through coil of wire

208
Q

Magnet will not continue to attract soft magnetic material even when material is turned around

True or False?

A

False

209
Q

What happens when soft magnetic material is brought away from magnet

A

will lose magnetism

210
Q

What happens when soft magnetic material is brought near a magnet

A

will become magnetised

211
Q

Define magnetically soft (2)

A

magnets which do not stay magnetic

e.g electromagnets

212
Q

Define magnetically hard (2)

A

stay magnetic once magnetised

e.g steel, iron

213
Q

How does insulation maintain electricity safety (2)

A

prevents wires from touching each other

prevents people from touching wires

214
Q

Electricity hazards (4)

A

long cables - trips/falls

water near sockets - water conductive –> connects person to mains supply (lethal)

pushing metal objects in sockets - connects person to mains supply

overloading sockets - too much current –> melt insulation and cause fire

215
Q

Formula of energy in terms of electricity

A

energy (joules) = current (amperes) x potential difference (volts) x time (seconds)

216
Q

Formula of power in terms of electricity

A

power (watts) = current (amps) x potential difference (volts)

217
Q

Define transducer

A

device which transfers energy from one form to another

218
Q

LDR resistance in light and dark (2)

A

high resistance in dark

low resistance in light

219
Q

Function of light-dependent resistors (LDRs)

A

light sensors

220
Q

Function of thermistors

A

temperature sensors

221
Q

Function of variable resistor (2)

A

changes resistance

controls amount of current in resistor

222
Q

What is the potential difference across a battery equal to in a series circuit

A

sum of potential difference across each lamp

223
Q

Calculating combined resistance for parallel circuit

A

1/Rc = 1/R1 + 1/R2

224
Q

Calculating combined resistance for series circuit (2)

A

Rc = R1 + R2

R1/R2 are resistors

225
Q

Parallel circuit current equation

A

current from source = sum of current in branches of parallel

226
Q

What is current measured using

A

ammeter

227
Q

Disadvantage of parallel circuits

A

battery will not last as long

228
Q

Advantage of parallel circuit (2)

A

light is brighter

if one lamp is broken circuit will still work

229
Q

Disadvantages of series circuit

A

if one lamp is broken circuit is broken

230
Q

Advantages of series circuit

A

battery last longer

231
Q

Switches parallel circuit

A

other lamp will continue to work even if lamp is broken

232
Q

Switches series circuit

A

lamps cannot be switched on/off independently

233
Q

Battery of Parallel Circuit (2)

A

battery pushes charge along 2 different paths

more charge flows each second

234
Q

Battery of Series Circuit (2)

A

must push same charge through one bulb

less charge flows each second

235
Q

Lightbulb of parallel circuit

A

same brightness

236
Q

Lightbulb of series circuit

A

lamps have same brightness

237
Q

Current of parallel circuit

A

current splits with part of it going through each component

238
Q

Current of series circuits

A

same electric current in each component in circuit

239
Q

Why is resistance inversely proportional to cross-section area (3)

A

bigger area –> more electrons to carry charge along conductor –> lower resistance

240
Q

Resistance relationship with cross-section area

A

inversely proportional

241
Q

Why is resistance proportional to length (3)

A

longer conductor –> electrons must travel more –> more likely to collide with metal ions

242
Q

Resistance relationship to length

A

proportional

243
Q

Why does the rate of increase for current decrease to a certain extent as potential difference increases

A

temperature rise –> particles in conductor vibrate more and give more resistance to electron flow

244
Q

Ohm’s law (2)

A

potential difference across component is directly proportional to current

resistance eventually becomes higher if temperature of conductor increases

245
Q

resistance unit

A

ohms (omega sign)

246
Q

potential difference unit

A

volts (V)

247
Q

Resistance equation

A

resistance = potential difference / current

248
Q

Where should you place a voltmeter

A

connected parallel across component being measured

249
Q

How is potential difference/voltage measured

A

voltmeter

250
Q

How is energy transferred in a circuit (2)

A

electrons given potential energy as they pass through power supply (battery)

transfer energy to circuit components as they move through a circuit

251
Q

Define potential difference

A

energy that a unit of charge transfers between one point and another

252
Q

Define electromotive force (2)

A

amount of energy to drive charge around a circuit

measured in volts

253
Q

What is charge measured in

A

coulombs (C)

254
Q

Current equation

A

current = charge/time (s)

255
Q

Define current

A

amount of charge flowing per second

256
Q

How do you measure current in an electrical circuit

A

ammeter

257
Q

What is a current measured in

A

amperes/amps (A)

258
Q

What charged particles is a current carried by

A

ions

259
Q

Name of forces between opposite charges

A

electrostatic forces

260
Q

Strength of electric field force factors (2)

A

closeness of particles - closer = larger force

amount of electrical charge - more charge = larger force

261
Q

An electric field does not have a direction
True or False?

A

False

262
Q

Define an electric field

A

a field around an object which the charges are not balanced

263
Q

How is an electric current produced

A

electrons flow from one place to another

264
Q

Define a static charge

A

unbalanced charge collected on the surface of an object

265
Q

What happens when you charge an object with static electricity (2)

A

adding or taking away electrons

charge on object becomes unbalanced

266
Q

Insulators or Conductors which are charged by being rubbed?

A

insulator

267
Q

Best conductor

A

silver

268
Q

Name a semi-conductor

A

silicon

269
Q

Define insulators

A

substances that do not allow electric charge to pass through them

270
Q

Define conductors

A

substances that allow electric charge to pass through them

Physics (3 decks)

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