Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Chem and Phys > AQA Physics Definitions > Flashcards

AQA Physics Definitions Flashcards

You may prefer our related Brainscape-certified flashcards:
Periodic Table flashcards Chemistry 101 flashcards AP® Chemistry flashcards Organic Chemistry 101 flashcards
1
Q

Specific charge

A

the charge in coulombs divided by the mass in kilograms or charge to mass ratio

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Isotope

A

Isotopes are nuclei with the same number of protons but a different number of neutrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Photo-electric effect

A

the emission of electrons from metal surfaces by incident light of an appropriate frequency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Work function

A

the minimum energy required for an electron to escape from the surface of a metal

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Threshold frequency

A

the minimum frequency of a photon to produce photoelectrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Electron volt

A

the energy given to an electron when it passes through a potential difference of 1V

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Ionisation energy of an atom

A

the minimum energy required to remove an electron from an atom in its ground state

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Excitation energy

A

the energy required to move an electron from a lower energy level to a higher energy level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Line spectra

A

the characteristic wavelengths of light produced by individual excited atoms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Electric current

A

the number of coulombs of charge passing a point every second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Potential difference

A

the work done per unit charge in moving charges from one point in a circuit to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Resistance

A

the ratio of potential difference across a component to the current through it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Ohmic conductor or resistor

A

the ratio of potential difference to current remains constant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Ohms law

A

the current through a component is proportional to the potential difference across it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Critical temperature

A

the temperature at or below which the resistivity of a superconductor becomes zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Kirchoff’s first law

A

the sum of the currents into the junction is zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Kirchoff’s second law

A

in any closed loop the sum of the emf equals the sum of the potential difference

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

EMF

A

the total energy supplied per coulomb to charges as they pass through the battery or cell (before losing energy to internal resistance)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Internal resistance

A

the resistance inside a cell, battery, or power supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Useful volts

A

the potential difference across the terminals of the power supply (terminal p.d.)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Lost volts

A

the potential difference across the internal resistance of the power supply

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Route mean square

A

the square root of the mean of all the square values

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Time base

A

the control on an oscilloscope which changes the time it takes for the beam to cross the screen horizontally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Y-gain

A

the control on an oscilloscope that changes the sensitivity of the vertical voltage scale

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Scalar

A

a physical quantity which has magnitude only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Vector

A

a physical quantity which has magnitude and direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Equilibrium

A

a object is in equilibrium when the resultant force on it is zero and the resultant torque is zero

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Couple

A

two equal an opposite forces acting on a body but not along the same line

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Moment/torque

A

the moment/torque about a point is the force multiplied by the perpendicular distance from the point to the line of action of the force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Principle of moments

A

for an object in equilibrium the sum of the clockwise moments equals the sum of anticlockwise moments. This apples about any point which is on or outside the object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Centre of mass

A

the point at which the whole mass of the object appears to act, and the point where a single force acting has no turning effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Displacement

A

the distance an object has moved in a particular direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Speed

A

distance divided by the time taken

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Velocity

A

the displacement of the object divided by the time taken

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Acceleration

A

the change in velocity divided by the time taken to change

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Parabolic path

A

the shape of the path of a particle moving with a component of motion at right angles to a constant resultant force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

Newton’s first law

A

an object remains at rest of moves with a constant velocity providing no resultant external force is applied

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Newton’s second law

A

for a constant mass the acceleration of an object is proportional to the resultant force applied to it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Newton’s third law

A

if object A applies a force F on object B, object B applies a force of -F on object A

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

Work

A

work done equals force multiplied by the distance moved in the direction of the force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

Power

A

power equals work done divided by time (rate of transfer of energy)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Principle of conservation of energy

A

energy cannot be created or destroyed; it can only be changed from one form to another

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Hooke’s law

A

the extension of a spring or material is proportional to the tensile force applied up to the limit of proportionality

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Elastic limit

A

the point beyond which a material or spring stretched will not return to its original length

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Tensile stress

A

tensile force divided by the cross-sectional area of the material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Tensile strain

A

the extension of a solid divided by its original length when deformed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Plastic behaviour

A

a material undergoing plastic behaviour will not return to its original shape after deforming forces are removed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Fracture

A

when a material breaks - materials are compared by their ultimate tensile stress; the tensile stress needed to break the material

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

Brittleness

A

a brittle material will not undergo plastic deformation before fracture

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Young’s modulus

A

tensile stress divided by tensile strain (assuming the limit of proportionality has not been exceeded)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Amplitude

A

the maximum displacement from the equilibrium position of an oscillating object

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

Frequency

A

the number of oscillations per second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Wavelength

A

the distance between two consecutive particles in a wave that are in phase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Wavespeed

A

the speed of energy transfer through the medium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Path difference

A

the extra distance one of the waves coming from two sources has to travel to reach a point

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Electromagnetic wave

A

a transverse wave consisting of a changing magnetic field at right angles to a changing electric field

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

Polarised waves

A

electromagnetic waves with an electric field vector in one plane only

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

Unpolarised waves

A

electromagnetic waves with an electric field vector in many directions

59
Q

Refractive index

A

the absolute refractive index of a substance is the speed of light in a vacuum divided by the speed of light in the substance

60
Q

Critical angle

A

the angle of incidence on a boundary between two media when the angle of refraction is 90

61
Q

Total internal reflection

A

TIR occurs when the angle of incidence is greater than the critical angle, the substance at the boundary has a lower refractive index, and all the light is reflected within the substance

62
Q

Step index fibre

A

there is a sudden change in refractive index between the core and the cladding

63
Q

Stationary wave

A

a stationary wave is formed by two waves of the same frequency and similar amplitude travelling in opposite directions

64
Q

Node

A

a point on a stationary wave with zero amplitude

65
Q

Antinode

A

a point on a stationary wave with maximum amplitude

66
Q

Fundamental frequency

A

the lowest frequency of a wave which will produce a stationary wave

67
Q

Coherence

A

coherent waves have the same frequency and a constant phase relationship/difference

68
Q

Fringe spacing

A

the distance between two consecutive maxima or minima in an interference pattern

69
Q

Impulse

A

force multiplied by the time for which the force acts on the body

70
Q

Principle of conservation of momentum

A

momentum in a collision is always conserved provided no resultant external forces are acting

71
Q

Elastic collision

A

kinetic energy is conserved

72
Q

Inelastic collision

A

kinetic energy is not conserved

73
Q

Explosive collision

A

kinetic energy is increased due to transfer of energy from the explosion

74
Q

Centripetal force

A

the resultant force applied to an object to keep it moving in a circle, directed towards the centre of the circle and at right angles to the direction of motion of the object

75
Q

Angular speed

A

the rate of change of angular displacement in radians for an object in circular motion

76
Q

Simple harmonic motion

A

the condition for SHM is that the acceleration is proportional, and in the opposite direction, to the displacement from the equilibrium position. The period of oscillation is independent of the amplitude

77
Q

Energy in SHM

A

the energy of the oscillator is proportional to the amplitude squared. For an undamped oscillator the total energy remains constant

78
Q

Free vibrations

A

the oscillator vibrates at its natural frequency

79
Q

Resonance

A

the frequency of oscillation of the driver equals the natural frequency, and so maximum energy transfer occurs

80
Q

Phase relationship in resonance

A

the driver leads the driven by a phase angle of pi/2 radians (90 degrees) or a time of T/4 seconds

81
Q

Forced vibrations

A

the oscillator vibrates at the frequency of the driver

82
Q

Newton’s law of gravitation

A

the gravitational force between two objects is proportional to the product of their masses, and the inverse square of the separation of their centres of mass. The constant of proportionality is the universal gravitational constant (G). The force is always attractive

83
Q

Field

A

an area in space that explains why one object will apply a force on another object without touching

84
Q

Gravitational field strength

A

the force per unit mass placed at that point in the field

85
Q

Electric potential (at a point)

A

the work done per unit positive charge in bringing a small test charge from infinity to that point

86
Q

Electric field strength

A

the force per unit charge on a small positively charged object placed at a point in the field

87
Q

Gravitational potential (at a point)

A

the work done per unit mass in bringing a small test mass from infinity to that point in the field

88
Q

Inverse square law

A

applies to the strength of radial fields; if the distance from the centre of the field is doubled the strength of the field is reduced by a factor of four

89
Q

Circular path

A

the path taken by a particle when force of constant magnitude is applied at right angles to the motion of the particle

90
Q

Capacitance

A

the charge stored per unit p.d. of a capacitor

91
Q

Time constant

A

the resistance times the capacitance, measured in seconds

92
Q

Magnetic flux density

A

this is a measure of the magnetic field strength, units Tesla

93
Q

Tesla

A

1 Weber per metre squared

94
Q

Magnetic flux

A

the component of the magnetic flux density at right angles to a surface multiplied by the area of the surface through which it passes (units Weber)

95
Q

Magnetic flux linkage

A

the amount of magnetic flux that passes through a coil or complete loop of wire, multiplied by the number of turns of the wire

96
Q

Fleming’s left hand rule

A

this predicts the relationship between the direction of force (movement, thuMb), the current (seCond finger) and the field direction (First Finger)

97
Q

Cyclotron

A

a device which uses an alternating electric field and a uniform magnetic field to accelerate charged particles

98
Q

Faraday’s law

A

the size of the induced EMF in a conductor is proportional to the rate of change of magnetic flux linkage

99
Q

Lenz’s law

A

the direction of induced current flows opposite to the change that produces it (conservation of energy)

100
Q

Transformer equation

A

the ratio of the number of turns in the primary coil and secondary coil equals the ratio of primary and secondary voltages

101
Q

Rutherford scattering

A

the deflection of alpha particles using thin gold film

102
Q

Absorption

A

when the energy of the ionising radiation is completely used to ionise atoms in a material

103
Q

Background radiation

A

the ionising radiation that is present without a radioactive source (from sun, rocks, medical uses, nuclear fallout from weapons)

104
Q

Random nature of radioactive decay

A

radioactive decay follows the laws of probability - one cannot predict which nucleus will decay or when

105
Q

Activity

A

the total number of particles emitted by a source per second (measured in Becquerel)

106
Q

Becquerel

A

the number of counts per second

107
Q

Half life

A

the time for half of the undecayed atoms to decay

108
Q

Decay constant

A

the constant that relates the rate of decay of a radioactive material to the number of undecayed particles in the sample

109
Q

Alpha particle

A

a helium nucleus emitted from a nucleus of an atom at about 1/10th the speed of light

110
Q

Beta particle

A

an electron emitted from the nucleus of an atom 9/10th the speed of light

111
Q

Electron capture

A

when a nucleus absorbs an electron from an atomic energy level close to the nucleus causing a proton to change to a neutron and an electron neutrino to be emitted, accompanied by the emission of a high energy photon when electrons drop down to fill the gap left by the absorbed electron

112
Q

Nuclear excited states

A

when the nucleus is left with excess energy after the emission of a particle - the nucleus has quantised energy levels and a gamma ray of fixed energy is emitted from the nucleus

113
Q

Radius of closest approach

A

the closest distance an alpha particle will get to a nucleus when fired directly towards it

114
Q

Electron diffration

A

the diffraction of a high energy electron by the nucleus

115
Q

Nuclear density

A

the density of nuclear matter

116
Q

Mass difference

A

the difference between the mass of all the individual protons and neutrons and the mass when they are combined together in a nucleus

117
Q

Binding energy

A

the energy released when the nucleus is formed from individual protons and neutrons

118
Q

Atomic mass unit (u)

A

the mass of a particle or nucleus measured in ‘u’ compared to the mass of a carbon 12 atom having a mass of exactly 12 u

119
Q

Binding energy per nucleon

A

the binding energy divided by the total number of protons and neutrons in a nucleus

120
Q

Fission

A

the splitting of a large nucleus into smaller nuclei

121
Q

Fusion

A

the joining together of smaller nuclei to form a larger nucleus

122
Q

Induced fission

A

slow moving (thermal) neutrons are absorbed by a large nucleus making it unstable, which then decays releasing energy and producing smaller nuclei

123
Q

Chain reaction

A

after induced fission occurs neutrons are released which will go on to produce further induced fission reaction

124
Q

Critical mass

A

the mass of nuclear matter is critical when every induced fission causes at least one further fission (this depends upon the mass and shape of the matter)

125
Q

Moderator

A

the material in a nuclear reactor that is used to slow the neutrons by collision (material usually water or carbon)

126
Q

Coolant in a nuclear reactor

A

a fluid used to stop a machine or device becoming dangerously hot. It is pumped through the core of a nuclear reactor to transfer the thermal energy to the heat exchanger which is used to boil water to drive turbines

127
Q

Control rods

A

these are made of a material that absorbs neutrons and changes the amount of neutron flux in the reactor hence changing the rate of fission (usually boron)

128
Q

Specific heat capacity

A

the heat energy needed to raise 1kg of the material by 1 kelvin without change of state

129
Q

Specific latent heat

A

the energy needed to change the phase of 1kg of a material

130
Q

Specific latent heat of vaporisation

A

the energy needed to change the state of 1kg of a material from liquid to gas without change of temperature

131
Q

Ideal gas

A

a gas that obeys Boyle’s law (pV=k) or the ideal gas equation (pV=nRT)

132
Q

Avagadro’s constant

A

the number of particles in one mole of carbon-12 (in exactly 12g of carbon-12)

133
Q

Molar mass

A

the mass of one mole of a substance

134
Q

Molecular mass

A

the mass of one particle in a gas

135
Q

Assumptions in the kinetic theory of gases

A
  • the particles apply a force on the walls of the container by collision
  • collisions of particles with the walls and eachother are elastic
  • no bonds between particles
  • gas particles move with random motion
  • there are a large number of particles
  • the volume of the particles is negligible compared to the volume of the container
  • contact time of collisions with walls is negligible compared with time between collisions with walls
136
Q

Frequency of a progressive wave

A

number of complete cycles/wavelengths passing

a point per second

137
Q

Why is gravitational potential negative

A

Gravitational potential is defined as zero at infinity, and as the force is attractive, work must be done to reach infinity, hence it is always negative

138
Q

Black hole

A

An object with an escape velocity greater than the speed of light

139
Q

Escape velocity

A

The velocity at which an objects kinetic energy is equal to minus its gravitational potential energy, or the minimum speed that will allow an object to escape the gravitational field

140
Q

Modal dispersion

A

Light rays enter fibre at different angles and so some travel longer distances. Use a single-mode fibre to prevent this

141
Q

Material dispersion

A

Different wavelengths of light travel at different speeds in the fibre. Use monochromatic light to prevent this

142
Q

Yield point

A

the stress at which a large amount of plastic deformation takes place with a constant load

143
Q

Internal energy

A

Internal energy is the sum of the randomly distributed kinetic energies and potential energies of the particles in a body

Chem and Phys (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions