definitions - p1 Flashcards
Alpha Decay
The process of an unstable nucleus emitting an alpha particle (two protons and two neutrons) to become more stable.
Annihilation
The process of a particle and its antiparticle colliding and being converted into energy.
Antiparticle
A corresponding particle with the same mass but opposite charge and conservation numbers.
Baryon Number
A quantum number that is conserved in all particle interactions, where baryons have a baryon number of +1.
Baryon
A class of hadron made up of three quarks; the proton is the only stable baryon.
Beta-Minus Decay
The process of a neutron turning into a proton, emitting a beta-minus particle (an electron) and an antineutrino.
Beta-Plus Decay
The process of a proton turning into a neutron, emitting a beta-plus particle (a positron) and a neutrino.
Electron Diffraction
The spreading of electrons as they pass through a gap similar to the magnitude of their de Broglie wavelength.
Electron-volt (eV)
Work done to accelerate an electron through a potential difference of 1V.
Energy Levels
Defined energies at which electrons can exist in an atom; electrons cannot exist between levels.
Excitation
The process of an electron taking in energy to move to a higher energy level.
Gauge Boson
Exchange particles that transmit the four fundamental interactions between particles.
Ground State
The most stable energy level that an electron can exist in.
Hadrons
A class of particles that experiences the strong nuclear interaction.
Ionisation
The process of an atom losing an orbital electron and becoming charged.
Isotope
Atoms with the same number of protons but different numbers of neutrons.
Isotopic Data
Data from isotopes used for purposes like carbon dating.
Kaon
A type of meson that decays into pions.
Lepton Number
A quantum number conserved in all particle interactions.
Lepton
Elementary subatomic particles, including electrons, muons, and neutrinos.
Meson
A class of hadron made up of a quark and an antiquark pair.
Muon
A type of lepton that decays into electrons.
Neutrino
A subatomic particle hypothesized to maintain the conservation of energy in beta decay.
Nucleon Number (A)
The sum of protons and neutrons in a nucleus.
Nucleon
A proton or neutron.
Pair Production
The process of a high-energy photon converting into a particle and its antiparticle.
Photon
A packet of energy.
Pion
A type of meson and the exchange particle for the strong nuclear force.
Positron
The antiparticle of an electron with a positive charge.
Proton Number (Z)
The number of protons in the nucleus of an element.
Stopping Potential
The minimum potential difference required to stop the highest energy electrons in the photoelectric effect.
Strange Particles
Particles produced through the strong interaction but decay via the weak interaction.
Strangeness
A quantum number conserved in strong interactions but not in weak interactions.
Strong Nuclear Force
Force that acts between nucleons to keep the nucleus stable.
Threshold Frequency
The minimum frequency needed for photoelectrons to be emitted from a metal plate.
Work Function
The minimum energy required to remove an electron from a metal’s surface.
Amplitude
A wave’s maximum displacement from its equilibrium position.
Antinode
A position of maximum displacement in a stationary wave.
Cladding
A protective layer on optical fibre to improve strength and prevent signal transfer.
Coherence
Waves with the same wavelength and frequency and a fixed phase difference.
Diffraction Grating
A device with hundreds of slits per millimetre used to analyze elements.
Diffraction
The spreading of waves as they pass through a gap of similar magnitude to their wavelength.
Electromagnetic Waves
Waves consisting of perpendicular electric and magnetic oscillations.
Frequency
The number of waves that pass a point in a unit time period.
Fringe Spacing
The distance between two adjacent bright or dark fringes.
Interference
Superposition of waves when two waves meet.
Laser
A light source that produces a coherent beam.
Longitudinal Wave
A wave with oscillations parallel to the direction of energy propagation.
Material Dispersion
Different wavelengths traveling at different speeds through optical fibre.
Modal Dispersion
Different angles of waves entering an optical fibre causing pulse broadening.
Node
A position of minimum displacement in a stationary wave.
Optical Fibre
A thin glass fibre through which signals are passed.
Path Difference
How far ahead one wave is compared to another, usually in terms of wavelength.
Phase Difference
Difference in phase between two points on a wave.
Phase
How far through the wave’s cycle a point is.
Polarisation
Restriction of a wave to oscillate in a single plane.
Pulse Broadening
Elongation of a signal down an optical fibre due to dispersion.
Refractive Index
Ratio of speed of light in a vacuum to speed in a given material.
Snell’s Law
Links a wave’s angle of incidence to its angle of refraction using refractive indexes.
Wave Speed
The product of a wave’s frequency and wavelength.
Stationary Wave
A wave that stores energy but does not transfer it.
Total Internal Reflection
Full reflection occurs at the inside boundary of an optical fibre.
Transverse Wave
A wave with oscillations perpendicular to the direction of energy propagation.
Wavelength
Distance between two identical positions on adjacent waves.
Young’s Double-Slit Experiment
Experiment demonstrating diffraction of light through two narrow slits.
Breaking Stress
The maximum stress an object can withstand before failure.
Brittle
An object that shows little strain before reaching breaking stress.
Centre of Mass
The single point through which all mass of an object acts.
Conservation of Energy
Energy cannot be created or destroyed; it can only change forms.
Conservation of Momentum
Total momentum of a system remains constant without external forces.
Couple
Two equal and opposite parallel forces causing rotation without translation.
Density
Mass per unit volume of a material.
Efficiency
Ratio of useful output to total input for a system.
Elastic Behaviour
Material returns to original shape when deforming forces are removed.
Elastic Collision
Total kinetic energy before and after collision remains the same.
Elastic Limit
Force beyond which an object will not return to its original shape.
Elastic Strain Energy
Energy stored when an object is stretched.
Equilibrium
Condition where resultant force and moment are zero.
Hooke’s Law
Extension of an elastic object is proportional to the force applied.
Impulse
Change of momentum of an object when a force acts on it.
Inelastic Collision
Total kinetic energy changes before and after a collision.
Moment
The product of force and the perpendicular distance to the pivot.
Momentum
Product of mass and velocity of an object.
Newton’s First Law
An object remains in its state of motion unless acted on by a force.
Newton’s Second Law
Sum of forces equals the rate of change of momentum.
Newton’s Third Law
For every action, there is an equal and opposite reaction.
Plastic Behaviour
Material does not return to its original shape after deformation.
Principle of Moments
Sum of clockwise moments equal to sum of anticlockwise moments for equilibrium.
Scalar
A quantity with only magnitude; examples include length and mass.
Spring Constant
Constant of proportionality for spring extension under force.
Stiffness
Measure of difficulty in stretching an object.
Tensile Strain
The ratio of extension to original length; unitless.
Tensile Stress
Force acting per unit area; measured in Pascals.
Terminal Speed
Maximum speed when resistive and driving forces balance each other.
Vector
A quantity with both magnitude and direction.
Young Modulus
Ratio of stress to strain for a given material.
Ammeter
Device measuring current in a circuit when connected in series.
Current
Rate of flow of charge in a circuit.
Electromotive Force
Energy transferred by a source to each unit charge passing through.
Internal Resistance
Resistance to charge flow within a source.
Light Dependent Resistor
A semiconductor whose resistance increases as light intensity decreases.
Ohmic Conductor
Conductor where current flow is proportional to potential difference.
Ohm’s Law
Current and voltage are directly proportional in an ohmic conductor.
Parallel Circuits
Components connected across each other in separate loops.
Potential Divider
Method of splitting potential difference using series resistors.
Resistance
Measure of difficulty for current to flow through a material.
Resistivity
Quantity proportional to an object’s resistance and area, and inversely to its length.
Resistors in Parallel
Identical potential difference across each resistor; current is split.
Resistors in Series
Identical current through each resistor; potential difference is split.
Series Circuits
Components connected end to end in a single loop.
Superconductor
Material with zero resistivity at or below its critical temperature.
Terminal Potential Difference
Potential difference across terminals of a power source.
Thermistor
Temperature sensitive semiconductor whose resistance increases with temperature decrease.
Voltmeter
A device measuring potential difference across components.
Angular Speed
Speed of an object’s angular rotation; equal to frequency multiplied by 2π.
Centripetal Acceleration
Acceleration of an object moving in circular motion.
Centripetal Force
Resultant force responsible for circular motion, acting towards the center.
Critical Damping
Damping that reduces displacement to equilibrium in quickest time without further oscillation.
Damping
Dissipation of energy from an oscillating system.
Forced Vibrations
Repeating oscillations at the frequency of a driver.
Free Vibrations
Oscillations not caused by a driver, occurring at natural frequency.
Overdamping
Damping more than necessary to stop oscillations, delaying return to equilibrium.
Radian
A unit of angle.
Resonance
Occurs when oscillation frequency equals a system’s natural frequency.
Simple Harmonic Motion
Motion where acceleration is proportional and opposite to displacement.
Underdamping
Damping where energy is gradually removed, decreasing amplitude slowly.
