Physics Definitions Flashcards
1
Q
The property of things to resist changes in motion
A
Inertia
2
Q
Every object continues in a state of rest, or of uniform speed in a straight line, unless acted on by a nonzero net force
A
Newtons first law of motion (law of inertia)
3
Q
In the simplest sense, a push or a pull
A
Force
4
Q
The vector sum of forces that act on an object
A
Net force
5
Q
An arrow drawn to scale, used to represent a vector quantity
A
Vector
6
Q
A quantity that has both magnitude and direction, such as force
A
Vector quantity
7
Q
A quantity that has magnitude but not direction, such as mass and volume
A
Scalar quantity
8
Q
The net result of a combination of two or more factors
A
Resultant
9
Q
The state of an object or system of objects, for which there are no changes in motion. An accord with newtons first law, if an object is at rest, the object stays at rest. If an object is moving, it’s motion continues without change.
A
Mechanical equilibrium
10
Q
For any object or system of objects and equilibrium, the sum of the forces acting equals zero
A
Equilibrium rule
11
Q
How fast an object moves ; the distance traveled per unit of time
A
Speed
12
Q
The speed at any instant
A
Instantaneous speed
13
Q
The total distance traveled divided by the time of travel
A
Average speed
14
Q
An object’s speed and direction of motion
A
Velocity
15
Q
A quantity that has both magnitude and direction
A
Vector quantity
16
Q
A quantity that has only a magnitude, not a direction
A
Scalar quantity
17
Q
The rate at which velocity changes with time ; the change in which velocity may be in magnitude, or direction, or both
A
Acceleration
18
Q
Motion under the influence of gravity only
A
Freefall
19
Q
Any push or pull exerted on an object, measured in newtons
A
Force
20
Q
The resistive force that opposes the motion or attempted motion of an object either passed another object with which it is in contact or through a fluid
A
Friction
21
Q
The quantity of matter in an object. More specifically, it is the measure of the inertia or sluggishness that an object exhibit in response to an effort made to start it, stop it, deflect it, or change in anyway it’s state of motion.
A
Mass
22
Q
The force upon an object due to gravity (mg)
A
Weight
23
Q
The fundamental SI unit of mass. 1 kg is the mass of 1 L of water at 4°C.
A
Kilogram
24
Q
The SI unit for force. 1 N is the force that will give an object of mass 1 kg in acceleration of 1 m/s^2
A
Newton
25
The quality of space an object occupies
Volume
26
The acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object.
Newton second law
27
The speed at which the acceleration of a falling object terminates, because a resistance balances gravitational force
Terminal speed
28
Terminal speed with direction specified
Terminal velocity
29
Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first
Newtons third law
30
Mutually perpendicular vectors, usually horizontal and vertical, whose vector sum is a given vector
Components
31
The product of the mass of an object and its velocity
Momentum
32
The product of the force acting on an object and the time during which it acts
Impulse
33
Impulse is equal to the change, in the momentum of the object that the impulse acts upon
Impulse momentum relationship
34
In the absence of an external force, the momentum of a system remains unchanged. Hence, the momentum before an event involving only internal forces is equal to the momentum after the event.
Law of conservation of momentum
35
A collision in which objects rebound without lasting deformation or the generation of heat
Elastic collision
36
A collision in which objects become distorted, generate heat, and possibly stick together
Inelastic collision
37
The product of the force and the distance moved by the force
Work
38
The time rate of work ; rate at which energy is expended
Power
39
The property of a system that enables it to do work
Energy
40
Energy to to the position of something or the movement of something
Mechanical energy
41
Energy that something possesses because of its position
Potential energy
42
Energy that something possesses because of its motion, quantified by the relationship
Kinetic energy
43
The work done on an object equals the change in the kinetic energy of the object
Work energy theorem
44
Energy cannot be created or destroyed ; it may be transformed from one form into another, but the total amount of energy never changes
Law of conservation of energy
45
A device, such as a lever or pulley, that increases or decreases a force, or simply changes the direction of a force
Machine
46
The work output of any machine cannot exceed the work input. An ideal machine, where no energy is transformed into thermal energy ; (work input = work output)
Conservation of energy
47
A simple machine consisting of a rigid rod pivoted at a fixed point called the fulcrum
Lever
48
The percentage of the work put into a machine that is converted into useful work output
Efficiency
49
The linear speed tangent to a curved path, such as in circular motion
Tangential speed
50
The number of rotations or revolutions per unit of time ; often measured in rotations or revolutions per second or per minute
Rotational speed
51
The property of an object to resist any change in its state of rotation : if rest the body tends to remain at rest ; if rotating, it tends to remain rotating and will continue to do so unless acted upon by an external net torque
Rotational inertia
52
The product of force and lever-arm distance, which tends to produce or change rotation
Torque
53
The average position of the mass of an object.
Center of mass
54
The average position of wait for the single point associated with an object where the force of gravity can be considered to act
Center of gravity
55
The state of an object in which it is not acted upon by a net force or a net torque
Equilibrium
56
A force directed toward a fixed point, usually the cause of circular motion
Centripetal force
57
And upward force a parent in a rotating frame of reference. It is a parent in the sense that is not part of an interaction, but is a result of rotation, with no reaction force counterpart.
Centrifugal force
58
The product of the mass of an object and it’s linear velocity
Linear momentum
59
The product of a bodies rotational inertia in rotational velocity about a particular access. For an object that is small compared with the radio distance, angular momentum can be expressed as the product of mass, speed, and radio distance of rotation.
Angular momentum
60
When no external torque acts on an object, or a system of objects, no change of angular momentum can occur. Hence, the angular momentum before an event involving only internal torques or no torques is equal to the angular momentum after the event.
Conservation of angular momentum
61
Every body in the universe attracts every other body with a force that, for 2 bodies, is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers
Law of universal gravitation
62
A law that relates the intensity of an effect to the inverse square of the distance from the cause. Gravity follows an inverse square law, as do the effects of electric, magnetic, light, sound, and radiation phenomena.
Inverse square law
63
The force that an object exerts on a supporting surface, which is often, but not always, due to the force of gravity
Weight
64
Being without a supported for us, as in freefall
Weightless
65
High or low tides that occur when the sun, earth, and the moon are all lined up so that the tides due to the sun in the moon coincide, make the high tides higher than average in the low tides lower than average
Spring tides
66
Tides that occur when the moon is midway between noon, and four, and either direction. Tides due to the sun in the moon partly cancel, making the high tide slower than average in the low tides higher than average.
Neap tides
67
The influence that a massive body extends into the space around itself, producing a force on another massive body. It is measured in newtons per kilogram.
Gravitational field
68
A concentration of mass that results from gravitational collapse, near which gravity is so intense that not even light can escape
Black hole
69
Any object that moves through the air or through space under the influence of gravity
Projectile
70
The curved path followed by a projectile under the influence of only constant gravity
Parabola
71
A projectile or small celestial body that orbits a larger celestial body
Satellite
72
The oval shaped path followed by a satellite. The sum of the distances from any point on the path to two points called foci is a constant. When the foci are together at one point, the ellipse is a circle. As the foci get farther apart, the eclipse becomes more eccentric.
Ellipse
73
The path of each planet around the sun is an ellipse with the sun at one focus
Kepler’s law 1
74
The line from the sun to any planet sweeps out equal areas of space an equal time intervals
Kepler’s law 2
75
The square of the orbital period of a planet is directly proportional to the cube of the average distance of the planet from the sun
Kepler’s law 3
76
The speed that a projectile, space probe, or similar object, must reach to escape the gravitational influence of earth or of another celestial body to which it is attracted
Escape speed
77
The smallest particle of an element that has all of the elements chemical properties
Atom
78
The haphazard movement of tiny particles suspended, and a gas or liquid that results from their bombardment by the fast moving atoms or molecules of the gas or liquid
Brownian motion
79
The number that designate the identity of an element, which is the number of protons in the nucleus of an atom
Atomic number
80
An electrically charged atom ; an atom with an excess or deficiency of electrons
Ion
81
Atoms with the same element that contain different numbers of neutrons
Isotopes
82
The standard unit of atomic mass, which is equal to 1/12 the mass of the most common atom of carbon
Atomic mass unit
83
A material in which atoms of different elements are chemically bonded to one another
Compound
84
A substance who’s components are mixed together without combine chemically
Mixture
85
Two or more atoms that bond together by a sharing of electrons
Molecule
86
A complementary form of matter, composed of atoms that have negative nuclei and positive electrons
Antimatter
87
Unseen and unidentified matter that is evidence by its gravitational pull on stars in the galaxies.
Dark matter
88
The linking together of atoms to form, larger structures, including solids
Atomic bonding
89
A mass of a substance per unit volume
Density
90
The property of immaterial by which it changes shape when a deforming force acts on it and returns to its original shape when the forces removed
Elasticity
91
The amount of stretch or a compression of an elastic material is directly proportional to the applied force
Hookes law
92
The study of how size affects the relationships among weight, strength, and surface area
Scaling
93
The ratio of forced to an area over which that force is distributed
Pressure
94
The upward force that a fluid exerts on and immersed object
Buoyant force
95
An immersed body is buoyed up by a force, equal to the weight of the fluid it displaces
Archimedes principle
96
A floating object displaces, a weight of fluid equal to its own weight
Principle of flotation
97
The pressure applied to emotionless fluid can find in a container is transmitted undiminished throughout the fluid
Pascals principle
98
The tendency of the surface of a liquid to contract in an area in those behave like a stretched elastic membrane
Surface tension
99
The rise of a liquid in a fine hollow tube or in a narrow space
Capillarity
100
The pressure exerted against bodies immersed in the atmosphere. Results from the weight of air pressing down from above.
Atmospheric pressure
101
A device that measures atmospheric pressure
Barometer
102
The product of pressure and volume is a constant for a given mass of confined gas as long as the temperature remains unchanged
Boyles law
103
An object in the air is buoyed up with a force equal to the weight of the displaced air
Archimedes principle for air
104
Where are the speed of a fluid increases, the internal pressure in the fluid decreases
Bernoulli’s principle
105
An electrified gas that contains ions and free electrons. Most of the matter in the universe is in the plasma phase.
Plasma
106
A measure of the average translational kinetic energy per molecule, any substance, measured in degrees Celsius, or Fahrenheit or in kelvins
Temperature
107
The lowest possible temperature that a substance may have — the temperature at which molecules of the substance have their minimum kinetic energy
Absolute zero
108
The energy that flows from a substance of higher temperature to a substance of lower temperature, commonly measured in calories or joules
Heat
109
The total of all molecular energies, kinetic plus potential, that our internal to a substance
Internal energy
110
The quantity of heat per unit mass required to raise the temperature of a substance by 1 Celsius degree
Specific heat capacity
111
The transfer of heat energy by molecular and electron collisions within a substance
Conduction
112
The transfer of heat energy in a gas or liquid by means of currents in the heated fluid. The fluid movies, caring energy with it.
Convection
113
The transfer of energy by means of electromagnetic waves
Radiation
114
The radiation emitted by earth to outer space
Terrestrial radiation
115
The rate of loss of heat from a warm object is proportional to the temperature differences between the object and its surroundings
Newtons law of cooling
116
Warming of the lower atmosphere by short wavelength radiation from the sun that penetrates the atmosphere, is absorbed by Earth, and is reradiated at longer wavelengths that cannot easily escape earths atmosphere
Greenhouse effect
117
1400 J/m^2 received from the sun each second at the top of earths atmosphere on an area perpendicular to the suns rays ; expressed in terms of power, 1.4 kW/m^2
Solar constant
118
Energy per unit time received from the sun
Solar power
119
The change of fees from liquid to gaseous
Evaporation
120
The change of phase from solid to gaseous, bypassing the liquid phase
Sublimation
121
The change of faze from gaseous to liquid
Condensation
122
The rapid evaporation that takes place within a liquid as well as at its surface
Boiling
123
The process of melting under pressure and then subsequently refreezing when the pressure is removed
Regelation
124
Device that transfers heat out of a cool environment and into a warm environment
Heat pump
125
The amount of energy required to change a unit mass of a substance from solid to liquid
Latent heat of fusion
126
The amount of energy required to change a unit mass of a substance from liquid to gas
Latent heat of vaporization
127
The study of heat, and it’s a transformation into different forms of energy
Thermodynamics
128
The lowest possible temperature that a substance can have
Absolute zero
129
The restatement of the law of energy conservation, apply to the systems in which energy is transferred by heat and or work
First law of thermodynamics
130
A process, often fast expansion or compression, in which no heat enters or leaves a system
Adiabatic process
131
A condition in which upward convection of air ceases, often because an upper region of the atmosphere, is warmer than the region below it
Temperature inversion
132
Thermal energy never spontaneously flows from a cold object to a hot object
Second law of thermodynamics
133
A device that uses heat as input in provides work as output
Heat engine
134
They measure of the disorder of a system. Whenever energy freely transformed from one form to another, the direction of transformation is toward a state of greater disorder, and therefore toward one of greater entropy.
Entropy
135
The waveform traced by simple, harmonic motion which can be made visible on a moving conveyor belt by a pendulum, swinging at right angles above the moving belt
Sine curve
136
For a wave or vibration, the maximum displacement on either side of the equilibrium (midpoint) position
Amplitude
137
The distance between successive crusts, troughs, or identical parts of a wave
Wavelength
138
For a vibrating body or medium, a number of vibrations per unit time. For a wave, the number of crests that pass a particular point per unit time
Frequency
139
The SI unit for frequency
Hertz
140
The time in which a vibration is completed. The period of a wave equals the period of the source and is equal to 1/frequency.
Period
141
A wave in which the medium vibrates perpendicularly to the direction in which the wave travels.
Transverse wave
142
A wave in which the medium vibrates parallel to the direction in which the wave travels
Longitudinal wave
143
The speed with which waves pass a particular point
Wave speed
144
The phenomenon that occurs when two waves meat, while traveling along the same medium
Wave interference
145
The pattern formed by the superposition of different sets of waves that produce reinforcement in some places and cancellation in others
Interference pattern
146
A stationary interference pattern formed in a medium when 2 sets of identical wave pass through the medium in opposite directions
Standing wave
147
The shift in received frequency due to the motion of a vibrating source toward or away from a receiver
Doppler effect
148
The V-shaped disturbance created by an object, moving across a liquid surface at a speed greater than the wave speed
Bow wave
149
The cone shaped disturbance created by an object moving at supersonic speed through a fluid
Shockwave
150
The loud sound that results from the incidence of a shockwave
Sonic boom
151
The highness or lowness of a tone ; related to a wave frequency
Pitch
152
Describes a sound that has a frequency too low to be heard by the normal human ear
Infrasonic
153
Describes a sound that has a frequency too high to be heard by the normal human ear
Ultrasonic
154
A condensed region of the medium through which a longitudinal wave travels
Compression
155
A rarefied (of reduced pressure) region of the medium through which a longitudinal wave travels
Rarefaction
156
The response of a body when a forcing frequency matches its natural frequency
Resonance
157
A result of super opposing different waves, often of the same wave length. Constructive interference results from crest to crest reinforcement. ; Destructive interference, results from crust to trough cancellation
Interference
158
The persistence of sound, as in an echo, due to multiple reflections
Reverberation
159
The bending of sound or any wave caused by a difference in wave speeds
Refraction
160
The setting up of vibrations in an object by a vibrating force
Forced vibration
161
The frequency at which an elastic object tends to vibrate when it is disturbed and the disturbing force is removed
Natural frequency
162
A series of alternate reinforcements and cancellations produced by the interference of two waves of slightly different frequencies, heard as a throbbing effect in sound waves
Beats
163
The power per square meter carried by a sound wave, often measured in decibels
Intensity
164
The characteristic sound of a musical instrument or a voice, which is governed by the number and relative intensities of partial tones
Quality
165
A single frequency component sound wave of a complex tone. When the frequency of a partial tone is an integer multiple of the lowest frequency, it is referred to as a harmonic.
Partial tone
166
The lowest frequency of vibration, or first harmonic, and a musical note
Fundamental frequency
167
A partial tone whose frequency is an integer multiple of the fundamental frequency. The second harmonic has twice the frequency of the fundamental, the third harmonic, three times the frequency, and so on in sequence.
Harmonic
168
A mathematical method that disassembles any periodic wave form into a combination of simple sine waves
Fourier analysis
169
A general term for electrical phenomena, much like gravity, has to do with gravitational phenomena, or sociology with social phenomena
Electricity
170
The study of electric charge at rest
Electrostatics
171
Electric charge is neither created nor destroyed. The total charge before an interaction equals the total charge after.
Conservation of charge
172
The relationship among electrical force, charge, and distance ; if the charges are alike, Insigne, the force is repulsive ; if the charges are unalike, the force is attractive
Coulomb’s law
173
The SI unit of electric charge
Coulomb
174
Any material that has free charged particles that easily flow through it when an electrical force acts on them
Conductor
175
Any material that does not contain free charged particles, and through which charged is not easily flow
Insulator
176
A material with properties that fall between those of a conductor and an insulator and whose resistance can be affected by adding impurities
Semiconductor
177
A material that is a perfect conductor, with zero resistance to the flow of electric charge
Superconductor
178
The transfer of electric charges between objects by rubbing or simply touching
Charging by contact
179
The distribution of electric charges in and on objects caused by the electric influence of a charged object close by but not in contact
Charging by induction
180
The term applied to an atom or molecule in which the charges are aligned, so that one side has a slight excess of positive charge and the other side a slight excess of negative charge
Electrically polarized
181
Electrical force per unit of charge. The field can be considered to be an aura surrounding charged objects and is a storehouse of electrical energy. About a charged point, the field decreases with distance, according to the inverse square law, like a gravitational field.
Electric field
182
The energy a charged object possesses by virtue of its location in an electric field
Electric potential energy
183
The electric potential energy per unit of charge, measured in volts ; often called voltage
Electric potential
184
An electrical device - in its simplest form, a pair of parallel conducting plates separated by a small distance - that stores electric charge and energy
Capacitor
185
The difference in electrical potential between two points, measured in volts
Potential difference
186
The flow of electric charge that transports energy from one place to another, measured and amperes (where 1 A is the flow of 6.25×10^18 electrons per second or 1 coulomb per second)
Electric current
187
The property of a material that resists electric current, measured in ohms
Electrical resistance
188
The statement that the current in a circuit fairies in direct proportion to the potential difference, or voltage across the circuit and inversely with the circuits resistance
Ohms law
189
Electrically charged particles flowing in one direction
Direct current (DC)
190
Electrically charged particles that repeatedly reversed direction, vibrating about relatively fixed positions.
Alternating current (AC)
191
The rate of energy transfer, or the rate of doing work ; the amount of energy per unit time, which can be computed as the product of current and voltage
Electric power
192
An electric current in which electrical devices are connected along a single loop of wire, such that the same current is in each device
Series circuit
193
An electric circuit in which electrical devices are connected in such a way that the same voltage ask across each one, and any single one completes the circuit independently of all the others
Parallel circuit
194
Between magnets, it is the attraction of unlike magnetic poles for each other in the repulsion between like magnetic poles. Between a magnetic field and a moving charge particle, it is a deflecting force due to the motion of the particle : the deflecting force is perpendicular to the velocity of the particle and perpendicular to the magnetic field lines. This force is greatest or not charged particle moves perpendicular to the field lines, and is smallest when it moves parallel to the field lines.
Magnetic force
195
The region of magnetic influence around a magnetic pole or a moving charged particle
Magnetic field
196
Clustered regions of aligned magnetic atoms. When these regions themselves are aligned with one another, a substance containing them as a magnet.
Magnetic domains
197
A magnet who’s field is produced by an electric current. It is usually in the form of a wire coil with a piece of iron inside the coil.
Electromagnet
198
High speed particles that travel throughout the universe
Cosmic rays
199
The creation of voltage, and a magnetic field changes with time. If the magnetic field within a close loop changes in any way, a voltage is induced in the loop.
Electromagnetic induction
200
The induced voltage in a coil is proportional to the product of its numbers of loops, the cross-sectional area of each loop, and the rate at which the magnetic field changes within those lips
Faradays law
201
Electromagnetic induction device that produces electric current by rotating a coil with an a stationary magnetic field. A generator converts mechanical energy to electric energy.
Generator
202
A device for transferring electric power from one coil of wire to another, by means of electromagnetic induction, for the purpose of transforming one value of voltage into another
Transformer
203
A magnetic field is created in any region of space in which an electric field is changing with time. The magnitude of the induced magnetic field is proportional to the rate of which the electric field changes. The direction of the induced magnetic field is at right angles to the changing electric field.
Maxwells counterpart to faradays law
204
An energy carrying wave emitted by a vibrating charge that is composed of oscillating electric and magnetic fields that regenerate one another
Electromagnetic wave
205
The range of electromagnetic waves, extending infrequency from radio waves to gamma rays
Electromagnetic spectrum
206
The property of materials to pass light in straight lines without being scattered
Transparent
207
The property of materials not to allow passage of light
Opaque
208
A shaded region that appears were light rays are blocked by an object
Shadow
209
The darker part of a shadow we’re all the light is blocked
Umbra
210
A partial shadow that appears were some but not all of light is blocked
Penumbra
211
An event in which the moon blocks light from the sun in the moon shadow falls on part of Earth
Solar eclipse
212
And event in which the moon passes into the shadow of earth
Lunar eclipse
213
The three colors - red, blue, and green - that, when added, in certain proportions, produce any other color in the visible light part of the electromagnetic spectrum, and can be mix equally to produce white light
Additive primary colors
214
Any two colors of equal brightness that, when added, produce the sensation of white light
Complementary colors
215
The three colors of absorbing pigment - magenta, yellow, and cyan - that, when mixed in certain proportions, can reflect any other color in the visible light part of the electromagnetic spectrum
Subtractive primary colors
216
The return of light rays from a surface
Reflection
217
Light takes the path that requires the least time when it goes from one place to another
Fermat’s principle of last time
218
The angle of reflection equals the angle of incidence
Law of reflection
219
The bending of an oblique ray of light when it passes from one transparent medium to another
Refraction
220
The minimum angle of incidence inside a medium at which a light ray is totally reflected
Critical angle
221
The total reflection of light traveling within a denser medium when it strikes the boundary with a less dense medium at an angle larger than the critical angle
Total internal reflection
222
A lens that is that you’re in the middle, then at the edges, and that refracts parallel rays to a focus
Converging lens
223
A lens thinner in the middle than at the edges, causing parallel rays to diverge as if from a point
Diverging lens
224
An image formed by light rays that do not converge at the location of the image
Virtual image
225
An image formed by light rays that converge at the location of the image. A real image, unlike a virtual image, can be displayed on the screen.
Real image
226
Distortion in an image, produced by a lens, which to some degree is present in all optical systems
Aberration
227
Every point on a wave front may be considered the source of secondary wavelets that spread out in all directions with a speed equal to the speed of propagation of the waves
Huygens’ principle
228
The bending of light that passes near the edge of an object or through a narrow slit, causing the light to spread
Diffraction
229
Overlapping and combining of waves
Superposition
230
The alignment of the transverse electric vibrations of electromagnetic radiation. Such waves of a line vibrations are said to be polarized.
Polarization
231
The two-dimensional microscopic interference pattern that shows three dimensional optical images
Hologram
232
The process of boosting, one or more electrons in an atom or molecule from a lower to higher energy level
Excitation
233
The distribution of wavelengths in the light from a luminous source
Emission spectrum
234
An optical instrument that separates light into its constituent wavelengths in the form of spectral lines
Spectroscope
235
A state of glowing while at high temperature, caused by electrons bouncing around over a dimension larger than the size of an atom emitting radiant energy in the process.
Incandescence
236
A continuous spectrum, like that of white light, interrupted by dark lines or bands, that result from the absorption of light of certain frequencies by a substance through which the radiant energy passes
Absorption spectrum
237
The property of certain substances to absorb radiation of one frequency, and to reemit radiation of lower frequency.
(occurs when an atom is boosted up to an excited state and loses its energy in two or more downward jumps to a lower energy state)
Florescence
238
A type of light emission that is the same as fluorescent, except for a delay between excitation and de-excitation, which provides an afterglow. The delay is caused by atoms being excited to energy states that do not decay rapidly. The afterglow may last from fraction of a second two hours, or even days, depending on the type of material, temperature, and other factors.
Phosphorescence
239
An optical instrument that produces a beam of coherent monochromatic light
- Light amplification by stimulated emission of radiation
Laser
240
An elemental unit of a quantity, a discrete amount of something
Quantum
241
One quantum of electromagnetic energy is called a ___________
Photon
242
The physics that describes the micro world, where many quantities are granular, not continuous, and where particles of light and particles of matter exhibit wave as well as particle properties
Quantum physics
243
A fundamental constant that relates the energy of light quanta to their frequency
Planck’s constant
244
The emission of electrons from a metal surface when light shines on it
Photoelectric effect
245
The principle stating that Planck’s constant sets a limit on the accuracy of measurement. According to it, it is not possible to measure exactly both the position in the momentum of a particle at the same time, nor the energy in the time during which the particle has that energy
Uncertainty principle
246
The principle, stating that the wave and particle aspects of both matter and radiation are necessary, complementary parts of a whole.
complementarity
247
The statement that frequencies of some spectral lines of the elements are either the sums of the differences of the frequencies of two other lines
Ritz combination principle
248
The theory of the micro world based on wave functions and probabilities developed, especially by Werner Heisenberg and Erwin Schrodinger
Quantum mechanics
249
A fundamental equation of quantum mechanics that relates probability wave amplitude to the forces acting on a system. It is a basic to quantum mechanics as newtons laws of motion are to classical mechanics.
Schrödingers wave equation
250
The rule that a new theory must produce the same result as the old theory where the old theory is known to be valid
Correspondence principle
251
The spontaneous emission of energetic particles by an atomic nucleus
Radioactivity
252
A stream of alpha particles ejected by certain radioactive elements
Alpha ray
253
A stream of electrons emitted during the radioactive decay of certain nuclei
Beta ray
254
High frequency electromagnetic radiation emitted by the nuclei of radioactive atoms
Gamma ray
255
The acronym for a unit of absorbed energy. Radiation absorbed dose. It is equal to 0.01 J of energy, absorbed per kilogram of tissue
Rad
256
The acronym for a unit used to measure the effect of ionizing radiation on humans. Roentgen equivalent man.
Rem
257
The elementary constituent particles or building blocks of nuclear matter
Quarks
258
The force that attracts nucleons to each other with in the atomic nucleus ; a force that is very strong at close distances, and greatly weakens as distance increases
Strong force
259
The conversion of an atomic nucleus of one element into an atomic nucleus of another element through a loss or gain of the number of protons
Transmutation
260
The process of determining the time that has elapsed since death by measuring the radioactivity of carbon from a sample due to the carbon 14 it contains
Carbon dating
261
The splitting of the nucleus of a heavy atom, such as uranium – 235, into 2 smaller nuclei, accompanied by the release of much energy
Nuclear fission
262
A self sustaining reaction in which the products of one reaction event stimulate for the reaction products
Chain reaction
263
The minimum mass of fissionable material in a reactor or nuclear bomb that will sustain a chain reaction
Critical mass
264
A fission reactor that is designed to breed more fissionable fuel than is put into it by converting non-fissionable isotopes to fissionable isotopes
Breeder reactor
265
A combination of light atomic nuclei to form heavier, nuclei, often with the release of much energy
Nuclear fusion
266
Nuclear fusion produced by high temperature
Thermonuclear fusion
267
And a vantage point with respect to which position and motion may be described (usually a set of coordinate axes)
Frame of reference
268
1. All laws of nature are the same in all uniformly moving frames of reference. 2. The speed of light in free space has the same measured value regardless of the motion of the source of the motion of the observer ; that is the speed of light is a constant
Postulates of the special theory of relativity
269
Occurrence at the same time. Two events that are simultaneous and one frame of reference need not be simultaneous in a frame that is moving relative to the first frame
Simultaneity
270
The fourth dimensional continuum, in which all events take place and all things exist. Three dimensions are the coordinates of space, and the fourth is time.
Space-time
271
The slowing down of time for a moving object, as measured by those who see it moving
Time dilation
272
The contraction of space in and observers direction of motion as a result of speed
Length contraction
273
The second of Einstein’s theory of relativity, which relates gravity to the properties of space and time
General theory of relativity
274
Because observations made in an accelerated frame of reference are indistinguishable from observations made in a gravitational field, any effect produced by gravity, can be duplicated by accelerating a frame of reference
Principle of equivalence
275
The lengthening of the waves of electromagnetic radiation escaping from a massive object
Gravitational red shift
276
The shortest path between two points in various models of space
Geodesic
277
A gravitational disturbance, generated by an accelerating mass, that propagates through space-time
Gravitational wave
