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Glossary Flashcards

1
Q

What does a.c. stand for?

A

Alternating current. The current from an a.c. supply constantly changes direction.

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2
Q

Define absolute refractive index.

A

The absolute refractive index (or simply, the refractive index), n, of a medium is the ratio of the speed of light in a vacuum to the speed of light in the medium.

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3
Q

What is an achromatic doublet?

A

A lens made from two different types of glass, to compensate for the fact that refractive index depends on the frequency of the incident light.

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4
Q

What is an alternator?

A

An a.c. generator.

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5
Q

What is the angle of incidence?

A

The angle between the incident ray and the normal.

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6
Q

What is the angle of refraction?

A

The angle between the refracted ray and the normal.

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7
Q

What does atomic number represent?

A

The number of protons in an atomic nucleus, determining the element.

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8
Q

What is binding energy?

A

The energy needed to split a nucleus into its separate nucleons.

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9
Q

What is blueshift?

A

Doppler-shifting of a light wave towards the blue end of the spectrum due to relative motion of the source towards the observer.

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10
Q

Define capacitance.

A

The ratio of electric charge to potential difference between any two conductors separated by an insulating material.

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11
Q

What is a capacitor?

A

Two (or more) conductors separated by an insulator that can be used to store charge.

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12
Q

What is a chain reaction?

A

When a nucleus undergoes fission, releasing neutrons that can collide with other nuclei, causing further fission reactions.

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13
Q

Define coherent waves.

A

Waves that have the same frequency, speed, and a constant phase relationship.

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14
Q

What is a collimator?

A

Part of a spectrometer used to produce a parallel beam of light.

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15
Q

What are components of a vector?

A

Two vectors which act at right angles, the vector sum of which is the original vector.

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16
Q

State the conservation of energy.

A

Energy cannot be created or destroyed, only converted from one form to another.

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17
Q

What is the conservation of momentum?

A

When two or more objects interact, the total momentum is conserved, in the absence of external forces.

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18
Q

Define critical angle.

A

The maximum value of the angle between the normal and the ray in glass for which refraction can occur.

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19
Q

What does d.c. stand for?

A

Direct current. The current from a d.c. supply always moves in the same direction around an electric circuit.

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20
Q

What is dark energy?

A

A theoretical form of energy postulated to act in opposition to gravity, accounting for most of the energy in the universe and causing its expansion to accelerate.

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21
Q

Define dark matter.

A

Thought to be a type of matter that does not interact with electromagnetic radiation, making it invisible to astronomers.

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22
Q

What is a depletion layer?

A

The area surrounding the p-n junction of a diode where electrons have combined with holes leaving no free charges.

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23
Q

What is diffraction?

A

An effect that causes waves to bend as they go past the end of an obstacle or through a small gap in a barrier.

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24
Q

Define dispersion.

A

The process of splitting up light into its constituent colours.

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25
What is displacement?
A specified distance from a fixed point, in a specified direction. Displacement is a vector quantity.
26
What is the Doppler effect?
The observed change in frequency of a wave caused by relative motion between the source and observer.
27
Define elastic collision.
A collision in which both momentum and kinetic energy are conserved.
28
What is electric current?
A net flow of charged particles.
29
What are electromagnetic waves?
The spectrum of waves that includes radio, visible light, X-rays, etc.
30
Define electromotive force.
The electrical potential energy given to each unit of charge that passes through the source.
31
What is energy yield?
The amount of energy released per unit mass of fuel.
32
What is an excited state?
Any atomic energy level higher than the ground state.
33
Define ferromagnetic materials.
Materials in which the magnetic fields of the atoms line up parallel to each other in regions known as magnetic domains.
34
What is fission?
The splitting of a large atomic nucleus into smaller fragments with the resultant release of excess energy.
35
What does forward-biased mean?
A diode connected in a circuit such that the p-type terminal is more positive than the n-type terminal.
36
Define frequency.
The number of complete cycles of a wave passing a given point in a given time, measured in hertz (Hz).
37
What is the fundamental unit of charge?
The magnitude of charge carried by one electron or one proton, equal to 1.60 x 10^-19 coulombs.
38
What is a gold leaf electroscope?
A device used to measure small amounts of charge.
39
What is a grating?
A transparent slide with a large number of equally-spaced grooves that acts as a source for coherent beams of light.
40
Define gravitational field.
The region of space around an object in which any other object with mass will have a gravitational force exerted on it.
41
What is gravitational field strength?
The gravitational field strength at a point is equal to the force acting per unit mass placed at that point.
42
What is the ground state?
The lowest energy level of an atom.
43
Define Hall effect.
The deflection of charge carriers in a conductor caused by a magnetic field.
44
What is a hologram?
A virtual image of an object that appears to be three-dimensional to an observer.
45
What does the Hubble-Lemaître law state?
A galaxy's velocity is proportional to the distance from the observer.
46
Define impulse.
The change of momentum of an object, equal to the product of the force acting on it and the time over which the force acts.
47
What is induced fission?
The deliberate splitting of a large nucleus caused by the collision of the nucleus with a neutron.
48
What is an inelastic collision?
A collision in which momentum is conserved but kinetic energy is not.
49
What does instantaneous mean?
At one point in time or at one particular instant in time.
50
What is internal resistance?
The opposition to current in a source of electrical energy.
51
Define intrinsic semiconductors.
Semiconductor material with no impurities.
52
What is the ionisation level?
The energy level at which an electron can break free from an atom.
53
Define irradiance.
The power per unit area of radiation incident on a surface.
54
What are isotopes?
Different forms of the same element with the same number of protons but different numbers of neutrons.
55
What is junction voltage?
The potential difference between the ends of the depletion layer inside a p-n junction diode.
56
Define kinetic energy.
The energy of an object due to its motion.
57
What is leakage current?
The tiny current in a reverse-biased diode.
58
What is a line absorption spectrum?
A spectrum that consists of narrow dark lines across an otherwise continuous spectrum.
59
What is a line emission spectrum?
A spectrum consisting of narrow lines of light, the position of which depends on the substances producing the light.
60
What is a load resistor?
The resistor or combination of resistors that forms the external part of an electrical circuit.
61
What are lost volts?
The potential difference that is used to drive a current through the internal resistance of a source.
62
Define magnetic domains.
Regions in a ferromagnetic material where the atoms are aligned with their magnetic fields parallel to each other.
63
What is a magnetic field?
A region in which a moving charge experiences a magnetic force.
64
What are magnetic poles?
There are two types of magnetic poles - north and south. Opposite poles attract, like poles repel.
65
Define mass defect.
The difference between the mass of a nucleus and the total mass of an equal number of individual nucleons.
66
What is mass number?
The total number of nucleons in the nucleus of an atom.
67
Define momentum.
The product of the mass of an object and its velocity.
68
What is a nuclide?
The nuclei of one particular isotope, all having the same atomic number and mass number.
69
What does Ohm's law state?
The current in a conductor at constant temperature is directly proportional to the potential difference across it.
70
What is an open circuit?
A circuit in which the current is zero due to a gap or infinite resistance.
71
Define path difference.
The difference in path lengths of two sets of waves.
72
What is a period in wave terms?
The time to make one complete wave, measured in seconds.
73
What is a photocathode?
The terminal from which electrons will be emitted due to the photoelectric effect.
74
What is a photodiode?
A type of p-n junction diode that responds to light intensity.
75
What is the photoelectric effect?
The emission of electrons from a metal due to the effect of electromagnetic radiation.
76
What are photoelectrons?
Free electrons produced by the photoelectric effect.
77
Define photoemission.
The emission of electrons from a material caused by light shining on it.
78
What is a photon?
The particle of electromagnetic radiation.
79
What is photovoltaic mode?
The mode of operation of a photodiode where it can supply power to a load.
80
Define point source.
A source of radiation with equal irradiance in all directions regarded as so small within its frame of reference.
81
What is potential difference?
The measure of the work done in moving one coulomb of charge between two points.
82
What is a potential divider?
A circuit consisting of resistors in series, connected across a supply, used as a source of fixed or variable p.d.
83
Define potential energy.
The energy stored in an object due to its position, shape, or state.
84
What is the principle of reversibility?
A ray of light will follow the same path in the opposite direction when it is reversed.
85
What is a projectile?
An object that is flying through the air under the influence of gravity, moving in two dimensions.
86
What is a P-type semiconductor?
Semiconductor material that has an excess of free holes.
87
Define radioactive decay series.
A chain of radioactive decays as a radioactive element changes to eventually become a stable, non-radioactive element.
88
What is a radioisotope?
Short for radioactive isotope.
89
What is a radionuclide?
Short for radioactive nuclide.
90
What is redshift?
Doppler-shifting of a light wave towards the red end of the spectrum due to relative motion of the source away from the observer.
91
Define refraction.
Occurs when a wave goes from one medium into another, changing speed and wavelength; frequency never changes.
92
What is resistance?
The opposition that a conductor offers to a current through it.
93
What does reverse-biased mean?
A diode connected in a circuit such that the p-type terminal is more negative than the n-type terminal.
94
Define scalar.
A physical quantity which has magnitude but no direction.
95
What is a short-circuit?
A circuit in which the current is at its maximum with zero resistance in the external circuit.
96
What is short-circuit current?
The maximum current that a source can supply with zero resistance in the external circuit.
97
What is a spectrometer?
An instrument that can make precise measurements of the spectra produced by different light sources.
98
Define spontaneous fission.
The random splitting of a large atomic nucleus due to internal processes within the nucleus.
99
What is stopping potential?
The minimum voltage required to reduce photoelectric current to zero.
100
What is a telescope?
The part of a spectrometer through which the spectrum is viewed.
101
What is terminal potential difference (t.p.d.)?
The potential difference that appears across the terminals of a source when supplying a current.
102
What is a thermistor?
A resistor in which the resistance depends on its temperature.
103
What is threshold frequency?
The minimum frequency of electromagnetic radiation that will cause photoemission for a particular substance.
104
Define total internal reflection.
When a ray of light meets a boundary with a less dense substance at an angle greater than the critical angle, it is all reflected inside the denser substance.
105
What is a turntable in a spectrometer?
The stage or platform on which the grating or prism sits, allowing for measurements.
106
What is the Universal Law of Gravitation?
States that there is a force of attraction between any two massive objects in the universe.
107
What is a valence shell?
The atomic energy level that contains the outermost electrons of the atom.
108
Define vector.
A physical quantity which has direction as well as magnitude.
109
What is velocity?
The rate of change of displacement.
110
What is weight?
The gravitational force acting on a mass.
111
What is a Wheatstone bridge circuit?
A resistor network used to measure resistance when balanced.
112
Define work function.
The minimum energy required to cause photoemission from a particular substance.

Higher physics (7 decks)

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