Paper 2 terminology Flashcards
1
Q
Archimedes’ principle
A
When a body is fully or partially submerged in a fluid, the upthrust is equal to the weight of the fluid displaced
2
Q
Breaking stress
A
The max stress a material can withstand without fracturing
3
Q
Brittle
A
A material that fractures without plastic deformation first
4
Q
Density
A
Mass per unit volume
5
Q
Ductile
A
A material that can withstand large plastic deformation without breaking
6
Q
Elastic deformation
A
When a material can return to it’s original shape after an applied stress without a permanent change to it’s shape
7
Q
Elastic limit
A
The maximum stress that can be applied to an object without plastic deformation
8
Q
Hooke’s law
A
The extension of an object is directly proportional to the force being applied to the object
9
Q
Laminar flow
A
A state of flow where layers of fluid move together in parallel with little or no mixing between layers
10
Q
Limit of proportionality
A
The point at which the stress on an object is so great that Hooke’s law no longer applies
11
Q
Plastic deformation
A
When a material is permanently deformed after an applied stress due to the atoms moving relative to one another in the material
12
Q
Stoke’s law
A
The magnitude of the force of viscosity acting on a spherical body as it moves through a fluid.
13
Q
Tensile strain
A
The extension of an object divided by its original length
14
Q
Tensile stress
A
The internal resistance of an object against a force that acts to deform it.
15
Q
Turbulent Flow
A
A state of flow where layers of fluid mix together unpredictably causing a chaotic state and eddys.
16
Q
Viscocity
A
A quantity measuring the internal friction of a fluid, acts to reduce the flow of a fluid
17
Q
Upthrust
A
The force felt against the weight of an object when fully or partially submerged in a fluid
18
Q
Yield point
A
The point of an F-x graph at which a material begins to rapidly extend without any additional stress
19
Q
Young’s Modulus
A
The ratio of stress to strain of an object. It is a measure of how stiff a material is
20
Q
Critical damping
A
Oscillations stop and return to equillibrium in quickest possible time
21
Q
Damping
A
When energy in a SHM system is not kept as KE or PE and total energy is no longer constant
22
Q
Free vibrations
A
System oscillates without driving force
23
Q
Forced oscillations
A
Systems oscillations forced by an external driving force
24
Q
Light damping
A
Oscillations amplitude reduces slowly
25
Natural frequency
Frequency at which a system naturally oscillates
26
Overdamoing
Damping is greater than critical damping, stops oscillations but system takes longer to return to equllibrium
27
Pendulum oscillator
Mass on a string that oscillate with simple harmonic motion from side to side
28
Resonance
Driving force=natural frequency of a system causing maximum energy transfer with amplitude of oscillations at maximum. Driving force is pi/2 radians ahead of phase of oscillations
29
SHM
There is always a restoring force pointing towards equillibrium which is proportional to the displacement
30
Spring oscillator
Mass on a spring that oscillates with SHM up and down
31
Equipotential
A plane of points with equal gravitational potential. The work done travelling
on an equipotential is zero.
32
Geostationary orbit
An orbit with a time period of one day and stay over one point on the
earth’s surface. They are directly above the equator and travel in the same direction as the
earth’s rotation.
33
Gravitational field
A region of space where objects with mass experience an attractive force
34
Gravitational field strength
The gravitational force on an object divided by it's mass. Acceleration due to the gravitational field
35
Gravitational potential
Amount of work done in moving a unit mass from an infinite distance to that point
36
Low orbit
160-2000 km
37
Newton's Law of gravitation
Force of gravity is proportional to the product of the masses
involved and inversely proportional to the square of the separation of the masses.
38
Synchronous orbits
Orbit with a time period of one day so will return to same point in sky each day
39
Activity
Number of nuclei that decay per second
40
Alpha
The radiation of a particle containing two protons and two neutrons. It is
strongly ionising, slow moving and positively charged so therefore deflected by a magnetic
field.
41
Atomic mass unit
1/12 the mass of a carbon 12 nuclei
42
Background radiation
Constant radiation everywhere that is due to radioactive substances in environment
43
Beta minus radiation
Radiation consisting of a high energy electron that is mildly ionising,
fast moving and negatively charged so therefore deflected by a magnetic field.
44
Beta plus radiation
Radiation consisting of a high energy positron that is mildly ionising,
fast moving and positively charged so therefore deflected by a magnetic field in the opposite
direction to beta-minus radiation.
44
Binding energy
The energy required to split a nucleus into its individual nucleons. The
greater the binding energy per nucleon the more stable the nucleus is.
45
Chain reaction
When fissions of one nuclei produces neutrons that cause fission in another nuclei
46
Control rod
Rod that absorbs neutrons, preventing further chain reactions
47
Coolant
A fluid that passes around the reaction vessel and carries away any thermal energy
produced by the fission reactions. This thermal energy is used to generate steam and drive
generators to produce electricity.
48
Cooling pond
Large pool of water that nuclear waste is placed into to allow it to cool to safe temp
49
Critical mass
minimum amount of fissile substance needed to maintain a chain reaction and a steady flow of fission
50
Decay constant
Probability of a decay occurring per unit time
51
Fuel rod
Contains fissionable material
52
Gamma radiation
High energy photons, weakly ionising, travels at c, no charge so not deflected by E/B fields
53
Half life
Time taken for half of the radioactive nuclei to decay
54
Moderator
substance inserted between the nuclear fuel that reduces the speed of the
neutrons coming from a fission reaction allowing them to become thermal neutrons that can
induce further fission.
55
Nuclear fission
Splitting of a large nucleus to produce smaller nuclei, fast moving neutrons and energy
56
Nuclear fusion
The fusing of two smaller nuclei to form a single nuclei producing a large
quantity of energy. Very high temperatures and pressures are needed as well as high
magnetic fields to contain the fusing plasma
57
Nuclear waste
The by-product of a nuclear reaction. This waste is no longer undergoing
fission that can be used due to the reduced activity but the waste is still radioactive and will
be for thousands of years so it is stored underground in reinforced containers.
58
Mass defect
The difference between the mass of the nuclei and its individual components.
If this mass defect is large and positive then when a nuclei undergoes fission this mass
defect is released as energy. If this mass defect is negative then when two nuclei are fused
together the mass defect is released as energy.
59
Spontaneous fission
Process where a nucleus splits without absorbing a thermal neutron
60
Thermal neutron
A slow moving electron that causes fission if absorbed by an unstable nuclei
61
Absolute zero
Particles of a substance have zero kinetic energy
62
Avogadro's constant
Constant number of particles per mole of a substance
63
Black body radiator
A perfect emmiter and absorber of all possible wavelengths of radiation
64
Boltzmann constant
A constant relating to the average Ek of the particle in a gas to the gas' temp
65
Boyle's law
As volume decreases, the pressure on a gas at a constant temperature increases
66
Charles' Law
As temperature increases, the volume of a gas at a constant pressure increases
67
Ideal gas
Hypothetical gas that has molecules with no interactions and occupy negligible space so it obeys the ideas gas law
68
Ideal gas law
combinations of Boyles, Charles and Pressure law that describes relationship between pressure, volume and temperature of an ideal gas
69
Internal energy
Sum of all the randomly distributed potential and kinetic energies of the particles that make up a substance
70
Luminosity
Total power radiated by a light emitting source
71
Pressure law
As temperature increases, pressure of a gas at a constant volume increases
72
Specific heat capacity
The energy required to raise the temperature of 1 kg of a
substance by 1 Kelvin without changing its state.
73
Specific latent heat
The energy required to change the state of 1 kg of a substance
without a change in temperature. Specific latent heat of fusion for solid to liquid and specific
latent heat of vapourization for liquid to gas.
74
State changes
During a state change a substance will not change kinetic energy,
temperature will be constant, but its potential energy will change, bonds will be broken or
formed.
75
Stefan-Boltzmann law
The luminosity of a black body radiator is directly proportional to its
surface area and its absolute temperature to the fourth power.
76
Wein's law
The peak wavelength of emitted radiation is inversely proportional to the
absolute temperature of the black body.
77
Astronomical unit
Mean distance of the earth to the sun
78
Big bang theory
Theory that the universe originated as a small, dense, hot region that expanded and then cooled
79
Cosmic microwavebackground radiaton
After big bang the universe was full of photons which interacted with matter in the universe. When the interactions stopped due to lower temperatures, photons become gamma rays and photons become microwaves due to redshift
80
Doppler effect
The apparent change in wavelength of a wave as source moves relative to an observer. For a source moving away the wavelength increases and for a sources moving towards observer wavelength decreases
81
Dark energy
Energy responsible for the acceleration in expansion of the universe which cannot be explained by observable energy
82
Dark Matter
Observations of galaxies show that they are more massive than they appear to be with the matter we can observe. Theory of dark matter to make up the unobservable mass
83
Giant star
Large star with higher luminosity that a main sequence star and a broad temperature range
84
Hertzsprung-Russel diagram
Visual representation of the lifecycle of a star. A plot of luminosity against temperature
85
Hubble's Law
The speed of a galaxy moving away from ours is proportional to it's distance away from us.
86
Light year
Distance travelled through space by a photon in a year
87
Luminosity
Total power radiated by a star
88
Main sequence star
A star that sits on the central band of stars on a Hertzsprung Russel diagram
89
Standard Candle
Objects of known luminosity used as references to measure other stars and to measure the distance to stars
90
Parallax
The change in position of an object depending on the viewing angle, can be used to estimate distance to a star based on how much is moves relative to background when earth has moved half an orbit
91
Parsec
Unit of distance. Distance to a star whose parallax angle is 1 arcsecond
92
Redshift
Shift in light of distant galaxies. Redshift is due to all galaxies moving away from each other and the larger redshift is due to galaxies moving away faster.
93
Supergiant
Very large luminous stars with temperature range 3500-20000K
94
White dwarf
Dense star similar mass to sun, similar size to earth. Final stage of low mass star's life with low luminosity
95
Absorption spectrum
Frequencies at which a certain element absorbs photons as these frequencies correspond to spacing between energy levels
96
Amplitude
Maximum displacement of vibrating particle or wave from equillibrium
97
Angle of incidence
Angle at which a light ray hits a medium
98
Angle of reflection
Angle at which a light ray reflects off a surface
99
Angle of refraction
Angle at which light rays travel after transferring into a different refractive index material.
100
Antinode
Point on a stationary wave where incoming and reflected waves are in phase producing a maximum
101
Coherence
Waves with the same frequency and constant phase difference
102
Constructive interference
Interference when two waves are in phase
103
Converging lens
A lens that takes parallel set of light rays and causes them to meet at a point
104
Critical angle
Angle of incidence where the angle of refraction is exactly 90 degrees
105
De Broglie hypothesis
All particles have a wave like nature and particle like nature. Wavelength of a particle is inversely proportional to the particle's momentum
106
De-excitation
Movement of an electron from a high energy level to a lower energy level. Causes photons to be released
107
Destructive interference
Interference when two waves are in antiphase
108
Diffraction
The spread of a wave as it passes through a gap or over an edge
109
Displacement
Distance and direction that a vibration particle or wave has travelled from its equillibrium position
110
Diverging lens
A lens that takes a parallel set of light rays and causes them to travel away from each other and not meet
111
Electron volt
Kinetic energy gained by one electron that is accelerated through a potential different of one Volt
112
Emission spectrum
When an element's atoms deexcite they move from one energy level to another with specific gap between levels. Creates a photon of that specific energy and frequencies of photons make up emission spectrum
113
Excitation
Movement of an electron from a low energy level to a higher energy level. Occurs when energy is transferred to an orbital electron
114
Focal length
Distance from the centre of the lens to the focal point
115
Focal point
Point at which rays of light passing through a lens converge
116
Frequency
Number of complete oscillations of a wave per second
117
Fundamental frequency
Oscillation of an entire object forming the lowest possible frequency for that object
118
Huygen's principle
Every point on a wavefront can be treated as a point source of secondary wavelets
119
Ionisation
When an electron is removed from an atom giving the atom a positive charge
120
Antiphase
Phase difference between two waves is 180 degrees or pi radians
121
In phase
Phase difference between two waves is 0 degrees or 0 radians
122
Intensity
Power transferred by a wave per unit area
123
Lens power
Inverse of the focal length
124
Longitudinal wave
A wave whose oscillations are parallel to the direction of energy transfer
125
Magnification
Object height divided by image height
126
Node
Point on stationary wave where incoming and reflected wave are in antiphase forming a minimum
127
One to one interaction
One photon transfers all of it's energy to a single electron in a photoelectric process
128
Path difference
For two waves starting from different points and arriving at the same point, path difference is difference in length travelled by each wave
129
Period
Time taken for a wave to complete one complete cycle
130
Phase
Where in the cycle of a wave a given point is in space and time
131
Phase difference
The difference in phase if the phase of two waves is determined at a single point in time
132
Photoelectric effect
When light of high enough energy shone on metal surface, electrons are emitted
133
Polarised wave
A wave whose oscillations have been restricted to the same plane
134
Principal axis
Axis passing through the centre of a lens.
135
Progressive lens
A wave that transfers energy from one point to another
136
Pulse echo technique
Ultrasound technique used for imaging of objects. Short pulses of ultrasound sent through medium and reflections recorded
137
Real image
Where rays of light have actually converged to produce an image and can be projected onto a screen
138
Refraction
When a wave changes speed when it crosses boundary into a new medium
139
Refractive index
A measure of how much the speed of light changes between two different media. Absolute refractive index is if one medium is a vaccum, otherwise it is relative refractive inde
140
Snell's Law
Relative refractive index can be found from the ratio of the sines of the angles of incidence and refractionS
141
Stationary wave
A wave that stores energy instead of transferring it
142
Superposition
When two waves meet at the same point in space their displacements combine and total displacement at that point becomes the sum of the individual displacements at that point
143
Threshold frequency
Minimum frequency of light needed to cause electrons to be emitted in the photoelectric effect regardless of intensity
144
Total internal reflection
When the angle of incidence is greater than the critical angle and the ray reflects at the surface and remains within the medium
145
Transverse wave
A wave whose oscillations are perpendicular to the direction of energy transfer
146
Ultrasound
Sound waves with a frequency greater than 20000Hz
147
Virtual image
When rays of light only appear to have converged and cannot be projected onto a screen
148
Wavefront
The surface made up of all points of the wave that are in phase with each other
149
Wavelength
Distance between two identical points on a wave
150
Wavespeed
Distance travelled by a wave per second
151
Work function
Minimum energy required to liberate an electron from the surface of a metal
