# Physics

?
• Created by: jklos5899
• Created on: 14-11-19 12:23
Absolute Uncertainty
A measurement showing how large the uncertainty is, and has the same units as the quantity being measured
1 of 340
Acceleration of free fall
The acceleration of a body falling under gravity
2 of 340
Acceleration
The rate of change of velocity measured in metres per second squared.
3 of 340
Accuracy
The degree to which a value obtained by an experiment is close to the true value
4 of 340
Ammeter
A device used to measure electric current, connected in series with the components
5 of 340
Ampere
S.I. unit for electric current
6 of 340
Amplitude
The maximum displacement of a wave from its mean position, measured in metres
7 of 340
Anomalous
Values in a set of data that do not fit the overall trend and so are judged not to be part of the inherent variation
8 of 340
Antinode
The displacement of the particles in a stationary wave.
9 of 340
Archimedes Principle
The upthrust exerted on an object immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the object displaces
10 of 340
Area
A physical quantity representing the size of part of a surface, measured in metres squared
11 of 340
Average Speed
A measure of the total distance travelled in a unit time
12 of 340
Braking Distance
The distance a vehicle travels while decelerating to a stop
13 of 340
Brittle
A material that breaks with little or no plastic deformation
14 of 340
Centre of Gravity
The point at which the entire weight of an object can be considered to act
15 of 340
Centre of Mass
The single point at which all of the mass of the object can be assumed to be situated. For a symmetrical body this will be in the centre.
16 of 340
Closed System
Any system in which all of the energy transfers are accounted for, energy or matter cannot enter or leave
17 of 340
Coherence
Two waves with a constant phase relationship
18 of 340
Components of a Vector
The results from resolving a single vector into horizontal and vertical parts
19 of 340
Components
Parts of electric circuits
20 of 340
Compressive Force
Two or more forces that have the effect of reducing the volume of the object on which they are acting, or reducing the length of the spring
21 of 340
Conductor
A material with a high number density of conduction electrons and therefore a low resistance
22 of 340
Conservation of Charge
Physical law stating charge is conserved in all interactions, it cannot be created or destroyed
23 of 340
Conservation of Energy
Physical law stating that energy cannot be created or destroyed, just transformed from one form to another or to another place. This is the situation in any closed system
24 of 340
Conventional Current
A model used to describe the movement of charge in a circuit, from + to -
25 of 340
Coulomb
Unit of electric charge, 1 C = 1 A x 1 s
26 of 340
Couple
Two forces that are equal and opposite to each other but not in the same straight line
27 of 340
de Broglie Equation
An equation expressing the wavelength of a particle as a ratio of Planck's constant and the particle's momentum, mv
28 of 340
Deformation
The change in shape or size of an object. If it returns to its original shape then the deformation is elastic
29 of 340
Degree Celsius
Unit for temperature
30 of 340
Density
Defined as mass per unit volume
31 of 340
Diffraction
When a wave spreads out after passing around an obstacle or through a gap
32 of 340
Displacement
The distance travelled in a particular direction, measured in metres
33 of 340
Displacement-Time Graph
A motion graph showing displacement against time for a given body
34 of 340
Distance
How far one position is from another, measured in metres
35 of 340
Drag Coefficient
A characteristic that determines the amount of drag that acts on an object
36 of 340
Drag
The resistive force that acts on a body when it moves through a fluid
37 of 340
Drift Velocity
The average velocity of an electron as it travels through a wire due to a p.d
38 of 340
Ductile
Can be drawn into wires and show plastic deformation under tensile stress before breaking
39 of 340
Efficiency
The ratio of useful output energy to total input energy
40 of 340
Elastic Deformation
The object will return to its original shape when the deforming shape is removed
41 of 340
Elastic Limit
The point at which elastic deformation becomes plastic deformation
42 of 340
Elastic Potential Energy
The energy stored in a stretched or compressed object measured in Joules
43 of 340
Elasticity
The property of a body to resume its original shape or size once the deforming force or stress has been removed
44 of 340
Electric Charge
Current x Time. Measured in Coulombs
45 of 340
Electric Current
A flow of charge. An S.I. quantity, measured in amperes and is a vector quantity
46 of 340
Electrolyte
A fluid that contains ions that are free to move and hence conduct electricity
47 of 340
Electromagnetic Wave
A self-propagating transverse wave that does not require a medium to travel through
48 of 340
Electromotive Force
The energy gained per unit charge by charges passing through a supply, when a form of energy is transferred to electrical energy carried by the charges. Measured in Volts or Joules per Coulomb
49 of 340
Electron Diffraction
The process of diffraction an electron through a gap
50 of 340
Electron Flow
The movement of electrons from - to +
51 of 340
Electron
Negatively charged sub-atomic particle. Conduction electrons travel around circuits creating an electric current
52 of 340
Electronvolt
The kinetic energy gained by an electron when it is accelerated through a potential difference of 1 volt
53 of 340
Energy
The stored ability to do work, measured in joules
54 of 340
Equations of Motion
The equations used to describe displacement, acceleration, initial velocity, final velocity and time when a body undergoes a constant acceleration
55 of 340
Equilibrium
When all the forces acting on an object in the same plane are balanced. There is zero net resultant force and in terms of motion, the object is either stationary or at constant velocity
56 of 340
Error Bars
Represent the absolute uncertainty in measurements and can be plotted in x and y directions
57 of 340
Extension
The change in length of an object when subjected to a tension, measured in metres
58 of 340
Fiducial Mark
An object placed in the field of view for the observer to use as a point of reference
59 of 340
First Harmonic
In the fundamental mode of vibration, the length of the string is half the wavelength. This produces the lowest possible frequency called the first harmonic
60 of 340
Fluid
A material that can flow from one place to another
61 of 340
Force Constant
The constant of proportionality in Hooke's Law measured in newtons per metre
62 of 340
Force
A push or pull on an object measured in newtons
63 of 340
Free Fall
When an object is accelerating under gravity
64 of 340
Frequency
The number of oscillations per unit time, measured in Hertz
65 of 340
Fundamental Frequency
The lowest frequency in a harmonic series where a stationary wave forms
66 of 340
Fundamental Mode of Vibration
Where the length of a string is half the wavelength, producing the lowest possible frequency called the first harmonic
67 of 340
Fuse
An electrical component designed to heat up, melt and break the circuit when a specified amount of current passes through it. Used as a safety device
68 of 340
Gamma Rays
A form of electromagnetic wave used for cancer treatment
69 of 340
Gradient of a Graph
The change in y-axis over the change in x-axis
70 of 340
Gravitational Force
The force due to a gravitational field acting on an object's mass
71 of 340
Gravitational Potential Energy
The energy stored in an object by virtue of the object being in a gravitational field, measured in Joules
72 of 340
Hard
Materials that resist plastic deformation by surface indentation or scratching
73 of 340
Harmonics
Whole number multiples of the fundamental frequency of a stationary wave
74 of 340
Hooke's Law
The extension of an object is proportional to the force that causes it, provided that the elastic limit is not exceeded
75 of 340
Impulse
The product of a force and the time taken for which the force acts
76 of 340
Infrared
A form of electromagnetic wave used in remote controls
77 of 340
Instantaneous Speed
The speed of an object at a given moment in time
78 of 340
Insulator
A material with a small number density of conduction electrons and therefore a very high resistance
79 of 340
Intensity
The rate at which energy is transferred from one location to another as the wave travels through space, perpendicular to the direction of wave travel.
80 of 340
Interference
The addition of two or more waves that results in a new wave pattern
81 of 340
Internal Resistance
The resistance to electric current of the materials inside chemicals, wires or components. When current flows, energy is transferred to these materials, resulting in the terminal p.d dropping
82 of 340
I-V Characteristic
A graph to show how electric current through a component varies with a potential difference across it
83 of 340
Joule
A unit of energy. 1 J is the work done when a force of 1 N moves its point of application 1 m in the direction of the force
84 of 340
Kelvin
S.I. unit of temperature
85 of 340
Kilowatt
Unit of power. 1 kW = 1000 W
86 of 340
Kilowatt-Hour
1000 watts for 3600 seconds
87 of 340
Kinetic Energy
The work an object can do by virtue of its speed, measured in Joules
88 of 340
Kirchhoff's First Law
The sum of the currents entering any junction is always equal to the sum of the currents leaving the junction
89 of 340
Kirchhoff's Second Law
The sum of the e.m.f is equal to the sum of the p.d. in a closed loop
90 of 340
Light Dependent Resistor
A component that changes its resistance with changes in the light intensity. Dark = High, Light = Low
91 of 340
Light Emitting Diode
A component that only allows electric current to pass through it in one direction and that emits light when a p.d. is applied across it
92 of 340
Longitudinal Wave
A wave where the oscillations are parallel to the direction of wave propagation
93 of 340
Lost Volts
The difference between the e.m.f. and the terminal p.d. when charge flows in the cell
94 of 340
Malleable
Can be hammered or beaten into flat sheets and show extensive plastic deformation when subjected to compressive forces
95 of 340
Malus' Law
A physical law describing the change in intensity of a transverse wave passing through a Polaroid analyser
96 of 340
Mass
S.I. quantity, measured in kilograms
97 of 340
Microwaves
A form of electromagnetic wave used in mobile phones
98 of 340
Moment of a Force
The product of a force and the perpendicular distance of its line of action from the point of axis. Also called turning moment
99 of 340
Monochromatic Light
Light waves with a single frequency or wavelength
100 of 340
Newton
The force that causes a mass of 1 kg to have an acceleration of metre per second every second
101 of 340
Nodes
Points in a stationary wave at which there is no displacement of the particles at any time
102 of 340
Ohm
Unit of resistance
103 of 340
Ohm's Law
The current through a conductor is directly proportional to the potential difference across it, provided that physical conditions remain constant
104 of 340
Order
The number of the pattern on either side of the central maximum
105 of 340
Parallel Circuit
A type of the circuit where the components are connected in two or more branches and therefore provide more than one path for the electric current
106 of 340
Percentage Difference
The difference between two values, divided by the average and shown as a percentage
107 of 340
Percentage Uncertainty
The difference between a measured and a true value expressed as a percentage
108 of 340
Period
The time taken for one complete pattern of oscillation, measured in seconds
109 of 340
Phase Difference
The difference by which one wave leads or follows another. In-phase waves are in step with each other. A completely out-of-phase wave is half a wavelength in front og the other.
110 of 340
Photocell
A component that reduces its resistance when light shines on it due to photoelectric emission of electrons
111 of 340
Photoelectric Effect
The emission of electrons from the surface of the material when electromagnetic radiation is incident on the surface
112 of 340
Photon
A quantum associated with electromagnetic radiation
113 of 340
Plane-Polarised Wave
A transverse wave only oscillating in one plane
114 of 340
Plastic Deformation
The object will not return to its original shape when the deforming force is removed, it becomes permanently distorted
115 of 340
Polarisation
The process of turning an unpolarised wave into a plane-polarised wave
116 of 340
Polymeric
Made of long chains of molecules called polymers
117 of 340
Polymeric Material
A material made of many smaller molecules bonded together, often making tangled long chains. These materials often exhibit very large strains
118 of 340
Potential Difference
The energy transferred per unit charge
119 of 340
Potential Divider
A type of circuit that uses two resistors in series to split or divide the potential difference of the supply in a chosen ratio so that a chosen p.d. can be provided to another device or circuit
120 of 340
Potential Energy
A form of stored energy
121 of 340
Power
The rate of doing work, measured in watts
122 of 340
Precision
The degree to which repeated values, collected under the same conditions in an experiment, show the same results
123 of 340
Pressure
Force per unit area at right angles to the area
124 of 340
Principle of Conservation of Energy
The total energy of a closed system remains constant. Energy can neither be created or destroyed, only transferred from one form to another
125 of 340
Principle of Conservation of Momentum
The total momentum before a collision is always equal to the total momentum after the collision, provided that no external forces are involved
126 of 340
Principle of Moments
For an object to be in rotational equilibrium, the sum of the clockwise moments must equal the sum of the anticlockwise moments
127 of 340
Progressive Waves
Waves that transfer energy away from a source
128 of 340
Quanta
The plural of quantum
129 of 340
Quantum
A small discrete unit of energy
130 of 340
Radian
Unit of angle or phase difference. One radian is the angle subtended at the centre of a circle by an arc of circumference that is equal in length to the radius of the circle
131 of 340
Radio Waves
A form of electromagnetic wave used in telecommunications
132 of 340
Random Errors
Give measurements that are scattered randomly above and below the true value when the measurement is repeated. A better result can be obtained by finding by finding the mean value of the results of several readings
133 of 340
Reflection
When waves rebound from a barrier, changing direction but remaining in the same medium
134 of 340
Refraction
When waves change direction when they travel from one medium to another due to a difference in wave speed from one medium to another
135 of 340
Resistance
A property of a component that regulates the electric current through it. Measured in ohms
136 of 340
Resistivity
The ratio of the product of resistance and cross-sectional area of a component and its length
137 of 340
Resolution of Vectors
Splitting a vector into vertical and horizontal components
138 of 340
Resultant Force
A single force that has the same effect as the sum of all the forces acting on a body
139 of 340
Resultant Vector
The sum of the two vectors forms the third side of the triangle
140 of 340
Scalar
A quantity that has magnitude but no direction
141 of 340
Semiconductor
A material with a lower number of conduction electrons than a conductor and therefore a higher resistance
142 of 340
Series Circuit
A type of circuit where the components are connected end to end and therefore provide only one path for the electric current
143 of 340
Significant Figures
The number of digits in a measured or calculated quantity that have a meaning and about which we can be certain
144 of 340
Spectrum
A collection of waves with a range of frequencies
145 of 340
Speed
The distance travelled per unit time
146 of 340
Spring Constant
Force per unit extension
147 of 340
Standing Wave
An alternative name for a stationary wave
148 of 340
Stationary Wave
A wave forned by the interference of two waves travelling in opposite directions
149 of 340
Stiffness
The ability for a material to resist a tensile force
150 of 340
Stopping Distance
The sum of the thinking distance and braking distance
151 of 340
Strain
Extension per unit length. Has no units and is dimensionless
152 of 340
Stress
Force per unit cross-sectional area. Unit of Pa
153 of 340
Superposition
The principle that when two or more waves of the same type exist at the same place, the resultant wave will be found by adding the displacements of the individual waves
154 of 340
Systematic Error
An error that does not happen by chance but instead is introduced by an inaccuracy in the apparatus or its use by the person conducting the experiment
155 of 340
Tensile Force
Usually two equal and opposite forces acting on a wire in order to stretch it. When both forces have the value T, the tensile force is also T, not 2T
156 of 340
Tensile Stress
The tensile force per unit cross-sectional area
157 of 340
Terminal p.d.
The potential difference recorded across the terminals of a cell. The difference between the e.m.f. and the terminal p.d. when charge flows is called lost volts
158 of 340
Terminal Velocity
The velocity at which the objects drag equals its accelerating force. Therefore there is no resultant force and zero acceleration
159 of 340
Thermistor
A component that changes its resistance based on its temperature. An NTC thermistors resistance reduces as the temperature increases
160 of 340
Thinking Distance
The distance travelled from seeing the need to stop to applying the brakes
161 of 340
Threshold Frequency
The lowest frequency of radiation that will result in the emission of electrons from a particular metal surface. For most metals, this occurs in the ultraviolet region
162 of 340
Thrust
A type of force due to an engine
163 of 340
Time Interval
S.I. quantity, measured in seconds
164 of 340
Torque
The turning moment due to a couple is the product of one of the forces and the perpendicular distance between them. The units are N m
165 of 340
Transverse Wave
A wave where the oscillations are perpendicular to the direction of the wave propagation
166 of 340
Triangle of Forces
If three forces acting at a point can be represented by the sides of a triangle, they are in equilibrium
167 of 340
Turning Forces
Forces that if unbalanced, will cause a rotation
168 of 340
Ultimate Tensile Strength
The maximum stress a material can withstand while pulled or stretched before it fails or breaks
169 of 340
Ultimate Tensile Stress
The maximum stress that can be applied to a material before it breaks
170 of 340
Ultraviolet
A form of electromagnetic wave that causes sun tanning
171 of 340
Upthrust
A force on an object due to a difference in pressure when immersed in a fluid
172 of 340
Vector
A quantity that has magnitude and direction
173 of 340
Vector Triangle
A type of scale diagram with two vectors, drawn tiptotail, to show how they can be added together
174 of 340
Velocity
The displacement per unit time, measured in metres per second
175 of 340
Velocity-Time Graph
A motion graph showing velocity against time for a given body
176 of 340
Volt
Unit of potential difference and e.m.f.
177 of 340
Voltmeter
A device used to measure the p.d. across a component. Is connected in parallel across a component
178 of 340
Volume
A physical quantity representing how much 3D space an object occupies, measured in metres cubed
179 of 340
Watt
Unit of Power
180 of 340
Wave
A series of vibrations that transfer energy from one place to another
181 of 340
Wavelength
The smallest distance between one point on a wave and the identical point on the next wave. Measured in metres
182 of 340
Wave-Particle Duality
The theory that all objects can exhibit both wave and particle properties
183 of 340
Weight
The gravitational force on a body, measured in newtons
184 of 340
Work Done
The product of the force and the distance moved by the force and the force in the direction of movement
185 of 340
Work Function
The minimum energy required to release an electron from a metals surface, overcoming the electrostatic attraction between the electron and the positive metal ions
186 of 340
Worst Fit
The worst acceptable line, still passing through all of the error bars. This will be either the steepest possible line of fit, or the least steep line of fit
187 of 340
X-Rays
A form of electromagnetic wave used in X-Ray photography
188 of 340
Young Modulus
The ratio between stress and strain, measured in pascals
189 of 340
Youngs Double Slit Experiment
An experiment demonstrating the wave nature of light via superposition and interference
190 of 340
Zero Error
A type of systematic error caused when an instrument is not properly calibrated or adjusted, and so gives a non-zero value when the true value is zero
191 of 340
Absolute Scale of Temperature
A temperature scale which is independent of the properties of any specific substance. Measured in Kelvin
192 of 340
Absolute Zero
The temperature at which a substance has minimal internal energy. The lowest limit of temperature
193 of 340
Absorption Line Spectrum
The pattern of dark line in a continuous spectrum from a light source, caused by light passing through an absorbing medium such as gas. The dark lines represent the wavelengths that are absorbed
194 of 340
Acoustic Impedance
Defined by the equation Z = pc. Where p is the density and c is the speed of sound in a material
195 of 340
Activity
The number of nuclear decays per unit time. An activity of one decay per second is called one becquerel
196 of 340
Alpha-Particle
A particle comprising two protons and two neutrons ejected from the nucleus during radioactive decay. It is identical to a helium nucleus and is emitted due to its unusually high stability as a particle
197 of 340
Alternating Current
Electrical current that reverses its direction with a constant frequency.
198 of 340
Angular Velocity
The rate of angular rotation, measured in radians per second
199 of 340
Annihilation
The process by which a particle and an antiparticle interact and their combined mass is converted into energy.
200 of 340
Antiparticle
A particle of antimatter that has the same rest mass but, if charged, an equal and opposite charge to its corresponding particle.
201 of 340
Astronomical Unit
The mean distance from the centre of the Earth to the centre of the Sun
202 of 340
Attenuation
A gradual decrease in intensity
203 of 340
Attenuation Coefficient
A constant used to calculate how the intensity of X-Rays decreases as they pass through a material.
204 of 340
Avogadro Constant (Na)
The number of particles in one mole of a substance
205 of 340
Beta-Minus Decay
Decay in which a neutron in the nucleus breaks down into a proton under the influence of a weak nuclear force, and a beta-minus particle and an electron antineutrino are emitted. A beta-minus particle is an electron.
206 of 340
Beta-Particle
A high-speed electron emitted from the nucleus during beta decay. It is produced when a neutron changes into a proton.
207 of 340
Beta-Plus Decay
Decay in which a proton in the nucleus breaks down into a neutron under the influence of the weak nuclear force, and a beta-plus particle and an electron neutrino are emitted. A beta-plus particle is a positron
208 of 340
Big Bang Theory
States that the universe was created from a single point where all of the universe's current mass was situated. At the time of its creation, the universe was much smaller, hotter, and denser than it is now. Time and Space were created at the Big Bang
209 of 340
Binding Energy
The minimum energy required to separate a nucleus into its constituent parts
210 of 340
Black Hole
The core of a massive star that has collapsed almost to a point. The density is so great a strong gravitational field is created. Appears black due to the escape velocity being greater than the speed of light
211 of 340
Boltzmann Constant
A constant used when relating the temperature of a gas to the mean translational kinetic energy of the particles in the gas. It can also be thought of the particles in the gas.
212 of 340
Boyle's Law
States that the volume of a fixed mass of gas is inversely proportional to the pressure exerted on the gas, under conditions of constant temperature.
213 of 340
Brownian Motion
The random movement of small visible particles suspended in a fluid due to collisions with much smaller, randomly moving atoms or molecules of the fluid.
214 of 340
Capacitance
The quantity of charge which can be stored per unit potential difference. Unit is Farad
215 of 340
Capacitor
A circuit component that stores energy by separating charges onto two electrical conductors with an insulator between them. One plate becomes positively charged and one becomes negatively charged
216 of 340
Carbon Dating
A technique used to determine the age of organic matter from the relative proportions of carbon-12 and carbon-14 isotopes that it contains, using the half life of carbon-14
217 of 340
Centripetal Acceleration
The acceleration of an object moving with uniform circular motion. The centripetal acceleration is directed radially inwards towards the center of the circle.
218 of 340
Centripetal Force
The resultant force on an object, acting towards the centre of the circle and causing the object to move in a circular path.
219 of 340
Chain Reaction
the sequence of nuclear reactions produced when an induced nuclear fission reaction triggers more than one further fission reaction
220 of 340
Chandrasekhar Limit
The maximum possible mass for a stable white dwarf star, equal to 1.4 times the mass of our Sun. Stars above this limit will collapse further to become black holes or neutron stars.
221 of 340
Collimator
A device for producing a parallel sided beam of electromagnetic radiation
222 of 340
Compton Scattering
The effect whereby an X-Ray deflected by an interaction with an orbital electron has a longer wavelength than its original wavelength. The electron is ejected from the atom at high speed.
223 of 340
Computerised Axial Tomography (CAT)
A process using multiple X-Ray scans to produce images of 'slices' through the body in one plane, in order to produce a 3D image.
224 of 340
Continuous Spectrum
A spectrum that appears to contain all wavelengths over a comparatively wide range.
225 of 340
Control Rod
A rod that can be lowered into the core of a nuclear reactor, absorb neutrons and slow down the chain reaction. Usually made of Boron
226 of 340
Cosmic Microwave Background Radiation (CMBR)
Microwave received from all over the sky originating from after the Big Bang, when the universe had cooled to 3000 K.
227 of 340
Cosmological Principle
States that on a large scale the universe is Isotropic (the same in all directions) and homogeneous (of uniform density).
228 of 340
Coulomb's Law
States that the electrical force between two point charges is directly proportional to the product of their charges and inversely proportional to the square of their seperation.
229 of 340
Damping
Damping forces reduce the amplitude of an oscillation with time, by removing energy from the oscillating system
230 of 340
Dark Energy
A type of energy that permeates the whole universe and opposes the attractive force of gravitation between galaxies via the exertion of negative pressure. It is not detected directly however it is known to exist due to the universe accelerating
231 of 340
Dark Matter
Matter which cannot be seen and does not emit or absorb EM radiation. It is not directly detected, however detected indirectly due to its gravitational effects relating to either the rotation of galaxies or by gravitational lensing of starlight
232 of 340
Decay Constant
The probability that an individual nucleus will decay per unit time.
233 of 340
Doppler Effect
The change in wavelength caused by relative motion between the wave source and the observer.
234 of 340
Driving Frequency
The frequency of the driving force applied to an oscillating object
235 of 340
Electric Field
The region around a body in which other charged bodies will feel a force due to the electric charge of the body
236 of 340
Electric Field Lines
Show the shape of the field. The direction of a field line at a point is the direction a positively charged would take if placed in that point.
237 of 340
Electric Field Strength
The force per unit positive charge. The force that a charge of +1C would experience if placed at that point in a field. Units are Newtons per Coulomb
238 of 340
Electric Potential
The work done per unit positive charge to move that charge from infinity to a point in an electric field.
239 of 340
Electromagnetic Induction
The process of inducing an e.m.f. in a conductor where there is a change in magnetic flux linkage across the conductor.
240 of 340
Electron Degeneracy Pressure
The pressure that stops the gravitational collapse of a low-mass star. This is the pressure that stops a neutron star from collapsing in on itself.
241 of 340
Emission Line Spectrum
The spectrum of frequencies of electromagnetic radiation emitted due to electron transitions from a higher energy level to a lower one within an atom.
242 of 340
Energy Levels
Electrons can only exist at certain energy values within an atom, occupying specific orbits at discrete energy levels
243 of 340
Equation of State of an Ideal Gas
pV=nRT
244 of 340
Escape Velocity
The minimum launch velocity required to move an object from a point in a gravitational field to a point at infinity
245 of 340
Exponential Decay
Where the quantity decreases at a rate that is proportional to the magnitude of the quantity at that time.
246 of 340
Faraday's Law
Faraday's Law of electromagnetic induction states that the magnitude of the induced e.m.f. is equal to the rate of change of flux linkage
247 of 340
Farad
The unit of capacitance. One farad is equivalent to one coulomb per volt
248 of 340
Fleming's Left Hand Rule
Shows the direction of the force on a conductor carrying a current in a magnetic field. Force = Thumb, Field = First Finger, Current = Second Finger. All at right angles to each other.
249 of 340
Forced Oscillations
Oscillations where an external force or driving force is applied to keep the body oscillating. The system oscillates at the frequency of the driving force that is causing the oscillations
250 of 340
Free Oscillations
Oscillations where there is no external force or driving force. The system oscillates at its natural driving frequency
251 of 340
Fundamental Particles
Particles that cannot be broken down into smaller components
252 of 340
Gamma Camera
Detects gamma photons emitted from a patient given a radioactive tracer. This is used to produce a real time image of the path of the tracer through the body
253 of 340
Gas Pressure
Acts in all directions at a point inside a gas, such as inside a star.
254 of 340
Generator
A device used to generate electricity, in which the work done to turn the coil within the magnetic field is transferred to electrical energy.
255 of 340
Geostationary Orbit
An orbit of the Earth made by a satellite that has the same time period and orbital direction as the rotation of the Earth and is in the equatorial plane
256 of 340
Gravitational Collapse
Inward movement of material in a star due to the gravitational force caused by its own mass. Gravitational collapse occurs in a mature star when the internal gas and radiation pressure can no longer support the stars own mass
257 of 340
Gravitational Field
The region around a body in which other bodies will feel a force due to the mass of a body
258 of 340
Gravitational Field Lines
Lines that show the shape of a gravitational field. The direction of a field line at a point is the direction in which a small mass would move if placed at that point
259 of 340
Gravitational Field Strength
The force acting per unit mass at a point in a gravitational field
260 of 340
Gravitational Potential
The work done in moving a unit mass from infinity to that point
261 of 340
Hadrons
Particles consisting of a combination of quarks to give a net zero or whole number charge. Neutrons and protons are hadrons
262 of 340
Half Life
The mean time taken for the activity of a source, or the number of undecayed nuclei present to halve
263 of 340
Hertsprung-Russell Diagram
A luminosity-temperature graph
264 of 340
Hubble's Law
States that the recessional velocity of a galaxy is directly proportional to its distance from the Earth
265 of 340
Ideal Gas
A gas that has internal energy only in the form of random kinetic energy
266 of 340
Ideal Gas Equation
pV=nRT
267 of 340
Impedance Matching
The reduction in intensity of reflected ultrasound at the boundary between two substances, achieved when the two substances have similar or identical acoustic impedences
268 of 340
Induced e.m.f
The e.m.f. produced by electromagnetic induction
269 of 340
Induced Nuclear Fission
Occurs when a nucleus absorbs slow-moving neutrons and the resulting unstable nucleus undergoes a fission reaction to split into two smaller nuclei and a small number of neutrons, releasing energy
270 of 340
Internal Energy
The sum of the randomly distributed kinetic and potential energies of all the atoms or molecules within a system
271 of 340
Isochronous
Constant and independent of amplitude. The period of an object with simple harmonic motion is isochronous
272 of 340
Isotopes
Atoms of the same element which contain the same number of protons but can have varying number of neutrons
273 of 340
Kepler's Third Law
States that the square of the period of a planet orbiting the Sun is proportional to the mean radius of its orbit cubed
274 of 340
Kinetic Model of Matter
States that all matter is made up of very small particles which are in constant motion. Allows explanation of the properties of matter and state changes
275 of 340
Lenz's Law
States that the direction of any induced e.m.f. or induced current is in a direction that opposes the flux change that causes it
276 of 340
Leptons
Fundamental particles. Electrons and Neutrinos are leptons
277 of 340
Light-Year
The distance travelled by light in one year.
278 of 340
Luminosity
The total energy a star emits per second
279 of 340
Magnetic Field
A region around a permanent magnet or a moving charge in which another body with magnetic properties will feel a force
280 of 340
Magnetic Field Lines
Show the shape and direction of a field.
281 of 340
Magnetic Flux Density
A measure of the strength of a magnetic field.
282 of 340
Magnetic Flux Linkage
The product of the magnetic flux through a coil and the number of turns on a coil.
283 of 340
Main Sequence Star
A star in the main part of it's life cycle, where it is fusing hydrogen to form helium in its core
284 of 340
Mass Defect
The difference in mass between the mass of a nucleus and the total mass of its separate nucleons
285 of 340
Maxima
Regions of brightness which will be seen when the path difference between overlapping waves is equal to a whole number of wavelengths
286 of 340
Mean Square Speed
The mean value of the square of velocity for a large number of gas particles moving randomly in a gas
287 of 340
Moderator
A substance used in a nuclear reactor which slows down neutrons so that they have a greater chance of being absorbed by the fissile nuclear fuel.
288 of 340
Mole
One mole of any substance is the amount of substance that contains as many particles as exactly 12.0g of carbon-12.
289 of 340
Natural Frequency
The frequency at which a system will oscillate when undergoing free oscillations
290 of 340
Neutrino
A fundamental particle with almost no mass and zero charge. Each neutrino has an antimatter partner, called an antineutrino
291 of 340
Neutron Star
The remains of the core of a red super giant after it has undergone a supernova explosion. Incredibly dense and composed of mainly neutrons
292 of 340
Newton's Law of Gravitation
States that the gravitational force of attraction between two point masses is directly proportional to the product of their masses and inversely proportional to the square of their seperation
293 of 340
Nuclear Fusion
The process of two nuclei joining together and releasing energy from a change in binding energy
294 of 340
Nucleon Number
The number of nucleons inside the nucleus of a particular atom
295 of 340
Pair Production
The process of creating a particle-antiparticle pair from a high-energy photon
296 of 340
Parsec
A unit of distance that gives a parallax angle of 1 second of arc, using the radius of the Earth's orbit as the baseline of a right angled triangle.
297 of 340
Period
The time taken for one complete pattern of oscillation at any point, measured in seconds.
298 of 340
Permittivity
A constant related to the size of the capacitance of a capacitor.
299 of 340
Permittivity of Free Space
A physical constant related to the size of the force between electric charges in free space.
300 of 340
Phase Difference
The fraction of a complete cycle or oscillation between two oscillating points, expressed in degrees or radians
301 of 340
Photomultiplier Tube
A device used to give a pulse of electrons for each incident photon
302 of 340
Piezoelectric Effect
The change in volume of a material when a p.d. is applied across its opposite faces. Alternatively, the production of an induced e.m.f. when certain crystals are placed under stress
303 of 340
Planetary Nebula
An expanding, glowing shell of ionised hydrogen and helium ejected from a red giant star at the end of its life
304 of 340
Positron Emission Tomography
The use of gamma photons, produced when positrons annihilate with electrons inside the body, to map out biologically active areas within the body
305 of 340
Proton Number
The number of protons inside the nucleus of a particular atom
306 of 340
Quarks
Components of hadrons, which have a fractional electric charge. They are believed to be fundamental particles.
307 of 340
Radian
One radian is the angle subtended at the centre of a circle when the arc is equal in length to the radius of the circle
308 of 340
Radiation Pressure
Outward pressure due to the momentum of photons released in fusion reactions. Acts in the direction of the energy flow
309 of 340
Red Giant
A star in the later stages of its life that has nearly exhausted the hydrogen in its core and is now fusing helium nuclei. It is bigger than a normal star because its surface layers have cooled and expanded.
310 of 340
Red Shift
The apparent increase in wavelength of electromagnetic radiation caused when the source is moving away, relative to the observer
311 of 340
Red Super Giant
A star that has exhausted all the hydrogen in its core and has a mass much higher than the Sun
312 of 340
Relative Permittivity
The factor by which the capacitance of a capacitor with that material between its plates is increased relative to the capacitance of the capacitor with air or vacuum between its plates
313 of 340
Resonance
Occurs in forced oscillations when the driving frequency is equal to the natural frequency of the system being forced to oscillate
314 of 340
Root Mean Square Speed
The square root of the mean square speed
315 of 340
Scintillator
A material that produces many photons of visible light when struck by a high-energy photon
316 of 340
Search Coil
A small, flat coil used to determine the strength of a magnetic field
317 of 340
Simple Harmonic Motion
Oscillation of a body in which its acceleration is directly proportional to its displacement from a fixed point and always directed towards that fixed point
318 of 340
Solenoid
A long coil of current carrying wire
319 of 340
Specific Heat Capacity
The amount of energy needed to raise the temperature of 1 kg of a substance by 1 K
320 of 340
Specific Latent Heat of Fusion
The amount of energy required to change the phase of 1 kg of a substance from a solid to a liquid
321 of 340
Specific Latent Heat of Vaporisation
The amount of energy required to change the phase of 1 kg of a substance from a liquid to a gas
322 of 340
Stefan's Law
Relates the luminosity of a star with its absolute temperature
323 of 340
Stellar Parallax
The apparent shifting in position of a star viewed against a background of distant stars when viewed from different positions of the Earth, such as at different positions of the Earth's orbit around the Sun
324 of 340
Strong Nuclear Force
A force that acts between nucleons and holds the nucleus together against the electrostatic repulsion of the protons
325 of 340
Supernova
A huge explosion produced when the core of a red super giant collapses
326 of 340
Thermal Equilibrium
A situation in which there is no net heat flow between two objects in contact with each other
327 of 340
Thermodynamic Scale of Temperature
A temperature scale which is independent of the properties of any specific substance
328 of 340
Time Constant
The time taken for the change remaining on a capacitor to decrease to about 37% of its initial value
329 of 340
Tracer
A radioactive substance either ingested by, or injected into, a patient. It emits gamma photons to be detected by a gamma camera
330 of 340
Transducer
A device, such as a microphone, which converts a non electrical signal into an electrical signal
331 of 340
Transformer
A device that can either increase or decrease the size of an alternating voltage with little loss of power
332 of 340
Transmission Diffraction Grating
A glass surface with a large number of very fine parallel grooves or slits, which is used to produce optical spectra by diffraction of transmitted light
333 of 340
Ultrasound
Longitudinal waves above the upper limit of the audible range, with frequencies greater than 20 000 Hz
334 of 340
Unified Atomic Mass Unit
Defined as one-twelfth of the mass of a carbon-12 atom
335 of 340
Velocity Selector
A device using perpendicular magnetic and electric fields to select charged particles travelling at a specific velocity, which leave the region of crossed fields without being deflected
336 of 340
Weak Nuclear Force
A force felt by both quarks and leptons. It can change quarks from one type to another or leptons from one type to another and is responsible for beta decay
337 of 340
Weber
One weber is the magnetic flux when a magnetic field of flux density one tesla passes at right angles through an area of one square metre
338 of 340
White Dwarf
The end product of a low mass star, when the outer layers have dispersed into space. Very dense with a high surface temperature and low luminosity
339 of 340
Wien's Displacement Law
Used to estimate the peak surface temperature of a star from the wavelength at which the star's brightness is maximum
340 of 340

## Other cards in this set

### Card 2

#### Front

The acceleration of a body falling under gravity

#### Back

Acceleration of free fall

### Card 3

#### Front

The rate of change of velocity measured in metres per second squared.

#### Back ### Card 4

#### Front

The degree to which a value obtained by an experiment is close to the true value

#### Back ### Card 5

#### Front

A device used to measure electric current, connected in series with the components

#### Back ## Comments

No comments have yet been made

## Similar Physics resources:

See all Physics resources »See all Everything resources »