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A Level Physics Definitions Paper 1 :check: - Coggle Diagram
A Level Physics Definitions Paper 1 :check:
Electricity
Ammeter:
A device that measures current in a circuit. Connected in series. An ideal ammeter has 0 resistance
Current:
The rate of flow of charge in a circuit
Electromotive Force (emf):
The energy transferred per unit of charge that passes through a component
Internal Resistance:
The resistance to the flow of charge within a source.
Light Dependent Resistor:
Light sensitive semiconductor. Resistance increases when light intensity decreases
Ohmic Conductor:
A conductor for which the current flow is directly proportional to the P.D across it (in constant conditions)
Ohms Law:
Current and P.D through an ohmic conductor held under constant conditions are directly proportional (proportionality constant = resistance)
Parallel Circuits:
Components are connected across each other
Potential Divider:
Method of splitting P.D by connecting resistors in series. Total P.D is split in the ratio of their resistances
Resistance:
A measure of how difficult it is for current to flow through a material/component
Resistivity:
A measure of how easily a material conducts electricity
Resistors In Parallel:
P.D is identical. Current is split. Total resistance = inverse of sum of the inverses of the resistances
Resistors In Series:
Current is identical. P.D is split in the ratio of their resistances. Total resistance = sum of resistances
Series Circuits:
Components are connected in a single loop (end to end)
Superconductor:
A material with 0 resistivity below its critical temperature
Terminal P.D:
P.D across the terminals of a power source. Is equal to the emf minus any voltage drop over internal R
Thermistor:
Temperature sensitive semiconductor. Resistance increases when temperature decreases
Voltmeter:
Device used to measure P.D across components. Connected in parallel. An ideal voltmeter has infinite resistance
Particles & Radiation
Alpha Decay:
Process of an unstable nucleus emitting an alpha particle to become more stable
Annihilation:
A particle and its antiparticle collide, are converted into energy and released as 2 photons of equal energy in opposite directions
Antiparticle:
All particles have a corresponding antiparticle with the same mass but opposite charge and conservation numbers
Baryon Number:
A quantum number that is conserved in all particle interactions. Can only be an integer.
Baryon:
A hadron, made up of 3 quarks. Proton is the only stable baryon.
Beta-minus Decay:
Neutron turns into a proton, and emits a beta- particle and an antineutrino
Beta-plus Decay:
A proton turns into a neutron, and emits a beta plus particle and a neutrino
Electron Diffraction:
The spreading of electrons as they pass through a gap similar to their de Broglie wavelength. Evidence of wave-like properties of electrons
Electron-volt:
The work done to accelerate an electron through a P.D of 1V. 1eV = 1.6x10^-19J
Energy Levels:
Distinct energies at which electrons can exist in an atom. Electrons cannot exist between energy levels
Excitation:
An electron receives enough energy to move to a higher energy level
Gauge Boson:
The exchange particles that transmit the four fundamental interactions between particles
Ground State:
The most stable energy level an electron can exist in
Hadrons:
A class of subatomic particle that experiences the strong nuclear force. Baryons or mesons.
Ionisation:
The process of an atom losing an orbital electron and becoming charged. An electron receives enough energy to be removed from the atom
Isotope:
An atom with the same number of protons but a different number of neutrons
Isotopic Data:
Data from isotopes that can be used for a purpose, e.g. carbon dating
Kaon:
A type of meson that decays into pions. Is a strange meson. up - antistrange
Lepton Number:
A quantum number that is conserved in all particle interactions. Both lepton and muon lepton numbers are conserved
Lepton:
Fundamental particles, e.g. electrons, muons, neutrinos
Meson:
A class of hadron, made of a quark - antiquark pair
Muon:
A type of lepton that decays into electrons. Electron is the only stable lepton
Neutrino:
A subatomic particle whose existence was hypothesised to maintain the conservation of energy in beta-decay
Nucleon Number:
The sum of the number of protons and neutrons in a nucleus
Nucleon:
A proton or neutron
Pair Production:
A photon with sufficient energy is converted into a particle antiparticle pair when interacted with (usually near a nucleus)
Photon:
A discrete packet of energy
Pion:
A type of meson, the exchange particle for the strong nuclear force
Positron:
A positively charged particle that is the antiparticle of an electron
Proton Number:
The number of protons in a nucleus
Stopping Potential:
The minimum P.D required to stop the highest KE electrons from leaving the metal plate during the photoelectric effect
Strange Particles:
Particles that are produced through the strong interaction but decay through the weak interaction
Strangeness:
A quantum number. Conserved in strong nuclear interactions, not conserved in weak nuclear. Shows that strange particles are always produced in pairs
Strong Nuclear Force:
A force that acts between nucleons to keep it stable. Attractive up to 3fm, repulsive below 0.5fm
Threshold Frequency:
Minimum frequency of photons required for photoelectrons to be emitted from the surface of a metal plate through the photoelectric effect. Equal to the metals work function divided by plancks constant
Work Function:
The minimum photon energy required to remove an electron from a metals surface
Waves
Amplitude:
A waves maximum displacement from its equilibrium position
Antinode:
A region of maximum displacement on a stationary wave
Cladding:
Protective layer on an optical fibre to improve tensile strength, prevent damage and is less optically dense than the core
Coherence:
Same wavelength, frequency and a fixed phase difference
Diffraction Grating:
A grating with many slits. Produces sharper interference patterns & to calculate atomic spacing
Diffraction:
The spreading of waves as they pass through a gap or round an obstacle
Electromagnetic Waves:
Waves that consist of perpendicular electric and magnetic oscillations
Frequency:
The number of complete waves that pass a point per unit time. Inverse of time period
Fringe Spacing:
Distance between two adjacent fringes
Interference:
The superposition of waves when two waves meet. In phase = constructive interference, out of phase = destructive interference
Laser:
A light source that produces a coherent beam of monochromatic light
Longitudinal Wave:
Wave oscillations are parallel the the direction of energy transfer e.g: Sound
Material Dispersion:
Waves of different wavelengths travel at different speeds through an optical fibre so reach the end at different times, causing pulse broadening. Fixed by using monochromatic light
Modal Dispersion:
Waves enter an optical fibre at slightly different angles so they take a different path and reach the end at different times. Causes pulse broadening
Node:
A region of no displacement on a stationary wave
Optical Fibre:
A thin glass fibre through which signals are passed. Usually have a cladding surrounding them
Path Difference:
A measure of how far ahead a wave is compared to another
Phase Difference:
The difference in phase between two points on a wave. In radians
Phase:
A measure of how far through the waves cycle a given points on the wave is
Polarisation:
Only allows a (transverse) wave to oscillate in a single plane
Pulse Broadening:
Elongation of a signal passed down an optical fibre due to modal or material dispersion
Refractive Index:
Ratio of the speed of light in a vacuum and the speed of light in a given material. Is how much a wave slows down when entering a material
Snells Law:
Law linking a waves angle of incidence to its angle of refraction n1sinθ1 = n2sinθ2
Speed:
The speed of a wave. Product of frequency x wavelength
Stationary Wave:
A wave that doesn't transfer energy. Formed when two or more progressive waves of the same frequency and amplitude pass through each other in opposite directions
Total Internal Reflection:
Occurs in optical fibres, full reflection occurs at the inside boundary of the fibre
Transverse Wave:
Wave oscillations are perpendicular to the direction of energy transfer e.g: EM waves
Wavelength:
Distance between two identical positions on tow adjacent waves. (Peak to peak or trough to trough)
Youngs Double Slit:
Experiment that demonstrates the diffraction of light by passing monochromatic light across two narrow slits and observing the resulting pattern of bright and dark fringes
Mechanics & Materials
Breaking Stress:
The maximum stress an object can withstand before failure occurs
Brittle:
A brittle object will show very little strain before reaching its breaking stress
Centre Of Mass:
The single point through which all the mass of an object can be said to act
Conservation Of Energy:
Energy cannot be created or destroyed, only transferred into different forms
Conservation Of Momentum:
Total momentum before == total momentum after, assuming no external forces act
Couple:
Two equal and opposite parallel forces that act on an object through different lines of action
Density:
The mass per unit volume of a material
Efficiency:
The ratio of useful output to total input for a given system
Elastic Behaviour:
Material will deform to its original shape after an external force is applied and removed. No permeant deformation
Elastic Collision:
Total kinetic energy before == total kinetic energy after in a collision
Elastic Limit:
The force beyond which an object will no longer deform elastically, and instead will deform plastically
Elastic Strain Energy:
The energy stored in an object when it is stretched. = to the work done to stretch the object / the area under a force-extension graph
Equilibrium:
Resultant forces and resultant moments acting on the object are equal to zero
Hooke's Law:
Extension of an elastic object will be directly proportional to the force applied to it up to the objects limit of proportionality
Impulse:
The change of momentum of an object when a force acts on it
Inelastic Collision:
Total kinetic energy is not conserved during a collision. KE before != KE after
Moment:
The turning effect of a force. The force x perpendicular distance from the point to the line of action of the force
Momentum:
The product of an objects mass and velocity
Newton's First Law:
An object will remain in its current state of motion unless acted on by a resultant force
Newtons Second Law:
F=ma, sum of forces acting on an object is equal to the rate of change of momentum of an object
Newton's Third Law:
Every action has an equal and opposite reaction. Equal and opposite force.
Plastic Behaviour:
Will not return to its original shape when deforming forces are removed. Permenant deformation
Principle Of Moments:
Sum of clockwise moments == sum of anticlockwise moments for an object in equilibrium
Scalar:
A quantity that only has a magnitude e.g.: Length, mass, temperature
Spring Constant:
Constant of proportionality for the extension of a spring under a force. Higher spring constant = greater force needed to achieve a given extension
Stiffness:
A measure of how difficult it is to stretch a given object
Tensile Strain:
The ratio of an objects extension to its original length. Has no unit
Tensile Stress:
The amount of force acting per unit area. unit Pa
Terminal Speed:
The maximum speed of an object that occurs when the resistive and driving forces acting on the object are equal to each other
Vector:
A quantity that has both a magnitude and direction
Young's Modulus:
The ratio of stress to strain for a given material. unit Pa
Measurements & Errors
Accuracy:
A measure of how close a measurement is to the true value
Precision:
A measure of how close a measurement is to the mean value.
Random Error:
Unpredictable variation between measurements that leads to a spread of values around the true value. Reduced by taking repeat measurements
Systematic Error:
Causes all readings to differ from the true value by a fixed amount. Cannot be corrected by repeats, use a different technique or apparatus (zeroed)
Repeatable:
The same experimenter can repeat a measurement using the same method and equipment and obtain the same value
Reproducible:
An experiment can be repeated by a different experimenter using a different method/apparatus and still obtain the same results
Resolution:
The smallest change in a quantity that causes a visible change in the measured reading
Uncertainty:
The interval that a value is said to lie within
Further Mechanics
Angular Speed:
A measure of the speed of an objects angular rotation
Centripetal Acceleration:
The acceleration of an object moving in circular motion.
Centripetal Force:
The resultant force responsible for an object moving in circular motion
Critical Damping:
The form of damping that reduces displacement of an oscillating object to its equilibrium position in the quickest time possible
Damping:
Dissipation of energy from an oscillating system. Reduces the amplitude of oscillations. Damping occurs when a force opposes the systems motion
Forced Vibrations:
Repeated up and down oscillations, at the frequency of a driver. small amplitude at high frequency, large at low frequency
Free Vibrations:
Oscillations that are not caused by a driver. An object will naturally oscillate at its natural frequency
Overdamping:
A system is damped more than required to stop oscillations. Takes longer for the system to return to equilibrium than for critical damping
Radian:
A unit of angle
Resonance:
Occurs when the frequency of oscillations is equal to the natural frequency of the oscillating system. Rate of energy transfer is at a maximum.
Simple Harmonic Motion:
Motion where the acceleration of an object is directly proportional, and in the opposite direction to its displacement
Underdamping:
Energy is gradually removed from the system and amplitude slowly decreases