Glossary Flashcards

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1
Q

Absolute magnitude

A

The magnitude a star would have if it were viewed from a distance of 10pc.

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2
Q

Absorption

A

Process of removing light or sound energy.

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3
Q

Absorption spectrum

A

Continuous spectrum crossed by dark lines or bands due to reduction of energy of particular frequencies when the light passes through a medium.

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4
Q

Acceleration

A

Change of velocity per unit time.

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5
Q

Amplitude

A

The maximum displacement of a vibrating particle.

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6
Q

Amplitude modulation

A

Process of transferring information by varying the amplitude of a wave.

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7
Q

Analogue

A

Continuously varying signal; its value is proportionally a physical quantity.

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8
Q

Annihilate

A

When a particle and its antiparticle meet, they destroy each other and become radiation.

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9
Q

Antinode

A

Fixed point in a stationary wave pattern where the amplitude is a maximum.

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10
Q

Antiparticle

A

There is an antiparticle for every particle. A particle and its corresponding antiparticle have equal rest mass and, if charged, equal and opposite charge.

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11
Q

Apparent magnitude

A

The magnitude of a star as it is observed from earth.

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12
Q

Asperity

A

Roughness of a surface.

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13
Q

Attack

A

The beginning of a musical sound when a note is played on an instrument.

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14
Q

Band spectrum

A

The coloured bands observed from molecules at high temperature; observed as a range of frequencies.

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15
Q

Bandwith

A

The range of frequencies in a transmitted signal.

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16
Q

Baryon number

A

Numbers assigned to quarks and hadrons that must be conserved in an interaction.

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17
Q

Baryons

A

A hadron consisting of three quarks.

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18
Q

Big Bang

A

Theory that all the energy of the universe originated from one point and that there universe began from expansion at that point.

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19
Q

Bit rate

A

Number of binary digits transmitted per second.

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20
Q

Black body

A

A body that emits all possible wavelengths for the temperature of that body.

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21
Q

Bosons

A

Particles, like photons, kaons and pions; gauge bosons carry the fundamental forces between particles.

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22
Q

Brightness

A

Observed intensity of a source.

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23
Q

Channel bandwidth

A

The range of frequencies allocated to a user.

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24
Q

Compressions

A

Regions of high pressure for a longitudinal wave.

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25
Q

Consonant

A

Two or more notes which when played together produce a pleasing sound.

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26
Q

Constructive interference

A

Interference in which two waves superpose to produce a wave with amplitude equal to the sum of the amplitudes of the two waves.

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27
Q

Continuous spectrum

A

Spectrum that contains no gas; all frequencies are present.

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28
Q

Critical angle

A

The angle of incidence that a light ray must exceed for total internal reflection to occur.

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29
Q

Critical temperature

A

Temperature at which a conduction of electricity becomes superconducting

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30
Q

Current

A

Rate of flow of charge.

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31
Q

Decay

A

Process occurring win radioactive particles emit radiation.

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32
Q

Decibel (dB)

A

Measure of sound intensity; an increase of 3dB is doubling of intensity.

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33
Q

Deep inelastic scattering

A

Scattering that occurs when a high energy particle collides with another particle producing new particles.

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34
Q

Demodulating

A

Process of retrieving information from a transmitted amplitude modulated or frequency modulated signal.

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35
Q

Destructive interference

A

Interference in which two waves superpose to produce a wave with amplitude equal to the difference in the amplitudes of the two waves.

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36
Q

Diffraction

A

Spreading of waves on passing a gap or near an edge.

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37
Q

Digital

A

Information sent in the form of binary digits.

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38
Q

Displacement

A

Distance from a reference point in a given direction.

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39
Q

Drag force

A

The force of fluid resistance on an object moving through the fluid.

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40
Q

Efficiency

A

The ratio of useful energy transferred (or useful work done) by the machine or device to energy supplied to it.

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41
Q

Elastic

A

A property that enables a solid to regain its shape after is has been deformed or distorted.

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42
Q

Elastic potential energy

A

Energy stored in a solid when it is extended or compressed by a force.

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43
Q

Electromagnetic wave

A

An electric and magnetic wave packet or photon that can travel through free space.

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44
Q

Electromotive force

A

The amount of electrical energy per unit charge produced by a source of electrical energy.

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45
Q

Electron energy level

A

Energies which electrons can have when bound to an atom.

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46
Q

Electron

A

Fundamental lepton that is a constituent of atoms.

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47
Q

Electroweak force

A

Term that describes the electromagnetic interaction and the weak interaction between particles.

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48
Q

Emission spectra

A

A spectrum that comes from a source without passing through an absorbing medium.

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49
Q

Equilibrium

A

Situation in which there is no resultant force acting on a body; the body remains at rest or travels at a constant velocity.

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50
Q

Error bar

A

Line representing the probable error on a graph.

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51
Q

Error of measurement

A

Uncertainty of a measurement.

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52
Q

Excitation

A

Process of electrons moving to a higher energy level.

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53
Q

Excited states

A

Electron states that are higher than the ground states.

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54
Q

Fourier synthesis/analysis

A

The process of determining which sinusoidal waves combine to produce a different periodic wave.

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55
Q

Free body

A

Diagram which shows the magnitude and direction of all forces acting upon an object.

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56
Q

Free fall

A

Situation when the only force acting on a falling body is gravitational.

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57
Q

Frequency

A

The number of cycles of a wave that pass a point per second, the number of of complete to and fro oscillations that occur per second.

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58
Q

Frequency modulation

A

Process of transferring information by varying the frequencies of a wave.

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59
Q

Fundamental particles

A

Particles that are not made from smaller particles.

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60
Q

Geostationary orbit

A

Orbit of a satellite that remains above the same point of the earths surface.

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61
Q

Graded index core

A

Glass fibre whose refractive index decreases from the centre to the edge.

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62
Q

Gravitational potential energy

A

Energy of an object due to its position relative to a particle or body that has mass.

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63
Q

Graviton

A

The particle that is thought to mediate the gravitational force.

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64
Q

Ground state

A

The lowest energy state that an electron can occupy in an atom.

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65
Q

Ground waves

A

Transmitted wave that travels along the surface of the earth.

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66
Q

Hadrons

A

Particles and antiparticles that can interact through the strong interaction.

67
Q

Harmonic

A

Frequencies that are a multiple of the fundamental frequency of an oscillator. f, 2f, 3f etc.

68
Q

Higgs boson

A

The particle that has been proposed as being responsible for the mass of particles.

69
Q

Impulse

A

Force on a body x time for which the force acts = change in momentum of a body.

70
Q

Inelastic

A

When a body undergoes an elastic process some energy that is supplied changes form so it is not recoverable in its initial form.

71
Q

Infrasound

A

Sound that has a frequency below the lowest audible sound (about 16Hz)

72
Q

Intensity

A

The energy per square metre that arrives on a surface each second.

73
Q

Interference

A

Formation of points of cancellation and reinforcement where two coherent waves pass through each other.

74
Q

Internal energy

A

The sum of the potential and kinetic energies of all the atoms in a body.

75
Q

Internal resistance

A

Resistance inside a source of electrical energy, the loss of pd per unit current in the source when current passes through it.

76
Q

Ion

A

Charged atom.

77
Q

Ionisation

A

Process of creating ions.

78
Q

Ionisation energy

A

Energy that has to be supplied to an atom to remove an electron.

79
Q

Ionising radiation

A

Radiation that is able to provide energy to ionise atoms.

80
Q

Isotopes

A

Atoms of an element with different numbers of neutrons and the same number of protons.

81
Q

Kinetic energy

A

Energy due to the motion of a body.

82
Q

Leptons

A

Collective term for fundamental particles.

83
Q

Line spectrum

A

Spectrum produced by diffraction gratings using radiation produced by excitation and relaxation of electrons in atoms.

84
Q

Longitudinal wave

A

Waves with a direction parallel to the direction of travel of the waves.

85
Q

Loudness

A

Subjective perception of the intensity of a sound.

86
Q

Luminosity

A

The property of a source that gives the perception of brightness of a source.

87
Q

Mesons

A

A hadron consisting go a quark and an antiquark.

88
Q

Modes

A

A possible frequency of vibration.

89
Q

Modulating

A

The process of changing the amplitude or frequency of oscillation of a wave.

90
Q

Moments

A

Force x perpendicular distance from the line of action of the force to the point.

91
Q

Momentum

A

Mass x velocity

92
Q

Multi path dispersion

A

The lengthening of a light pulse as it travels along an optical fibre due to rays that repeatedly undergo total internal reflection having to travel a longer distance than rays that undergo less total internal reflection.

93
Q

Musical interval

A

An interval between two notes on a musical scale determined by the ratio of frequencies of the notes.

94
Q

Natural frequency

A

The oscillation that takes place when an oscillating system is displaced from its original position and allowed to vibrate freely.

95
Q

Node

A

Fixed point on a stationary wave pattern where the amplitude is zero.

96
Q

Nucleon number

A

The number of neutrons and protons in a nucleus; also referred to as mass number.

97
Q

Nucleon

A

Neutron or proton in the nucleus.

98
Q

Nuclide

A

A nucleus with a particular number of protons and neutrons.

99
Q

Octave

A

Musical interval between harmonics that have frequency f and 2f.

100
Q

Ohm’s law

A

The pd across a metallic conductor is proportional to the current provided by the physical conditions do not change.

101
Q

Oscilloscope

A

Instrument that produces an image of the variation with time of p.d.

102
Q

Pair production

A

When a gamma photon changes into a particle and antiparticle.

103
Q

Path difference

A

The difference in distances from two coherent sources to an interference fringe.

104
Q

Perfect pitch

A

The ability to identify the musical pitch of a note exactly.

105
Q

Period

A

Time for one complete cycle of a wave to pass a point; time for one complete oscillation.

106
Q

Phase difference

A

The fraction of a cycle between the vibrations of two vibrating particles, measured either in radians or degrees.

107
Q

Photoelectric effect

A

Emission of electrons from a metal surface when the surface is illuminated by a frequency greater than a minimum value known as threshold frequency.

108
Q

Photon

A

Packet or ‘quantum’ of electromagnetic waves.

109
Q

Pitch

A

Subjective quality relating to the position of a note on a musical scale determined by its frequency.

110
Q

Polarised

A

Transverse waves that vibrate in one plane only.

111
Q

Positron

A

Antiparticle of the electron.

112
Q

Potential difference

A

Work done or energy transfer per unit charge between two points when charge moves from one point to the other.

113
Q

Power

A

Rate of transfer of energy.

114
Q

Precision of an instrument

A

The smallest non zero reading that can be measured.

115
Q

Projectile

A

An unpowered object thrown or fired through the air.

116
Q

Pulse code modulation

A

Modulation in which a signal is sampled and only certain discrete values of the information are transmitted binary coded signal.

117
Q

Quality

A

The property that enables instruments of the same pitch to be recognised: determined by the frequencies present in the sound.

118
Q

Quantised

A

Only certain discrete values of a physical quantity are possible.

119
Q

Quarks

A

Fundamental particles that combine to form hadrons (baryons and mesons).

120
Q

Radiation

A

Energy transmitted as em waves or particles (alpha and beta).

121
Q

Random error

A

Error of measurement due to readings that vary randomly with no recognisable pattern.

122
Q

Range of set of a readings

A

The range of set of a readings of the same measurement is the difference between the minimum and maximum reading.

123
Q

Range of an instrument

A

The difference between the minimum and the maximum reading that can be obtained using an instrument.

124
Q

Rarefactions

A

Regions of low pressure for a longitudinal wave.

125
Q

Rays

A

Paths taken by energy, e.g light

126
Q

Recessional speed

A

Speed at which galaxies are moving away from the Earth.

127
Q

Red shift

A

The movement of waves to longer wavelengths than those observed from a similar source in a laboratory on earth.

128
Q

Reflection

A

Process in which a wave or particle is directed back into the medium from which it came when it is incident on a surface.

129
Q

Relaxation

A

The process in which an excited returns to a lower energy state by emitting a photon.

130
Q

Repeaters

A

Used to boost the energy of a signal during transmission.

131
Q

Resistance

A

Pd / current .

132
Q

Resistivity

A

Resistance per unit length x area of cross section.

133
Q

Resonating

A

A condition when the body is begin driven by a frequency that is equal to its natural frequency leading to a maximum amplitude of vibration.

134
Q

Resultant

A

Combined effect of a number of vector quantities (e.g force or velocity).

135
Q

Sampling

A

A process of taking the value of a physical quantity at regular intervals for transmission or processing.

136
Q

Scalars

A

A physical quantity of a magnitude only.

137
Q

Sky waves

A

Transmitted radio waves that are received back on earth after being deflected by the ionosphere.

138
Q

Space waves

A

Short wavelength radio waves that penetrate the ionosphere and can only be used for line of sight communication with the earth.

139
Q

Standing wave

A

Wave pattern with nodes antinodes formed when two or more progressive waves of the same frequency and amplitude pass through each other.

140
Q

Strangeness

A

A strangeness number is assigned to every particles and antiparticle on the basis that strangeness in always conserved in the strong interaction by not the weak interaction or decay involving a quark or antiquark.

141
Q

Strong force

A

Attractive force between nucleons that holds them in the nucleus.

142
Q

Superposition

A

The effect of two waves adding together when they meet.

143
Q

Third

A

Interval between the first and third note of a major musical scale.

144
Q

Threshold frequency

A

Minimum frequency of light that can cause photoelectric effect.

145
Q

Threshold of hearing

A

Lowest intensity of sound that is audible.

146
Q

Timbre

A

The property that enables instruments of the same pitch to be recognised: determined by the frequencies present in the sound.

147
Q

Torque

A

Force x perpendicular distance from the line of action of the force to the point.

148
Q

Total internal reflection

A

A light ray travelling in a substance is totally internally reflected at a boundary with a substance of lower refractive index if the angle of induce is greater than a certain value known as critical angle.

149
Q

Transverse wave

A

Waves with a direction of vibration perpendicular to the direction of propagation of the wave’s energy.

150
Q

Travelling waves

A

Waves for which the position of maximum displacement moves so that the wave is propagated.

151
Q

Tremolo

A

A note played by a continually changing that amplitude of the note or a continuous rapid change between two notes.

152
Q

Ultrasound

A

Sound that has a higher frequency than the highest audible sound (20,000 Hz).

153
Q

Ultraviolet catastrophe

A

The failure of classical physics to explain the nature of radiation from a black body.

154
Q

Unbalanced force

A

A force for which there is not an equal and opposite force acting on a particular object.

155
Q

Vector

A

A physical quantity with magnitude and direction.

156
Q

Velcocity

A

Change of displacement per unit time.

157
Q

Vibrato

A

A note played with a slight quick continually varying pitch.

158
Q

Viscosity

A

Property of a fluid (liquid or gas) to oppose the motion within it.

159
Q

Wavefronts

A

A surface or line along which all oscillations for a given frequency are in phase (wavefronts are perpendicular to rays).

160
Q

Wavelength

A

Distance qual to the least distance between two successive crests or compressions.

161
Q

Wave-particle duality

A

Matter particles have a wave like nature as well as a particle like nature, photons have a particle like nature as well as wave like nature.

162
Q

Work

A

Force x distance moved in the direction of the force.

163
Q

Work function

A

Minimum amount of energy needed by an electron to escape a metal surface.