component 3 Flashcards
Progressive wave
A pattern of disturbances travelling through a medium and carrying energy with it, involving the particles of the medium oscillating about their equilibrium positions
Transverse wave
A transverse wave is one where the particle oscillations are at right angles to the direction of travel (or propagation) of the wave.
Longitudinal Wave
A longitudinal wave is one where the particle oscillations are in line with (parallel to) the direction of travel (or propagation) of the wave
Polarised wave
A polarised wave is a transverse wave in which particle oscillations occur in only one of the directions at right angles to the direction of wave propagation.
Waves in Phase
Waves arriving at a point are said to be in phase if they have the same frequency and are at the same point in their cycles at the same time.
Diffraction
Diffraction is the spreading out of waves when they meet obstacles, such as the edges of a slit. Some of the wave’s energy travels into the geometrical shadows of the obstacles.
The principle of superposition
The principle of superposition states that if waves from two sources [or travelling by different routes from the same source] occupy the same region then the total displacement at any one point is the vector sum of their individual displacements at that point.
Phase difference
Phase difference is the difference in position of 2 points within a cycle of oscillation. It is given as a fraction of the cycle or as an angle, where one whole cycle is 2π or 360 degrees], together with a statement of which point is ahead in the cycle
Coherence
Waves or wave sources, which have a constant phase
difference between them (and therefore must have the same frequency) are said to be coherent.
Stationary wave
A stationary wave is a pattern of disturbances in a medium, in which energy is not propagated. The amplitude of particle oscillations is zero at equally-spaced nodes, rising to maxima at antinodes, midway between the nodes
Snell’s law
At the boundary between any two given materials, the ratio of the sine of the angle of incidence to the sine of the angle of refraction is a constant
Electron Volt
This is the energy transferred when an electron moves
between two points with a potential difference of 1V between them.
So for an electron being accelerated it is the kinetic energy acquired when accelerated through a pd of 1V.
Ionisation energy
The ionization energy of an atom is the minimum energy needed to remove an electron from the atom in its ground state.
Ionisation
The removal (or addition) of 1 or more electrons from (or to) an atom
Decay constant, λ
The probability of an individual nucleus decaying in 1 second
Leptons
Leptons are electrons and electron-neutrinos, also muons. They only experience the weak force, and different particles have their own particle specific lepton number (e.g. an anti electron neutrino couldn’t help conserve the lepton number of a muon)
Hadrons
Hadrons are particles consisting of quarks or antiquarks bound together. Only hadrons (and quarks or antiquarks themselves) can ‘feel’ the strong force
Baryons
A baryon is a hadron consisting of 3 quarks or 3 antiquarks. The best known baryons are the nucleons, i.e. protons and neutrons
Mesons
A meson is a hadron consisting of a quark-antiquark pair.
Kaons are mesons, and they always have a strange (or anti s) particle.
Unified atomic mass unit, u
The unified atomic mass unit is defined as exactly one twelfth of the mass of one atom of carbon-12. Thus one atom of carbon-12 has a mass of exactly 12 u.
Binding energy
The energy that has to be supplied in order to dissociate a nucleus into its constituent nucleons. Equal to mass defect
Mass-energy conservation
Energy cannot be lost or gained, only transferred from one form to another. We can measure the energy in a body by multiplying its mass by c^2.
Magnetic field, B (or magnetic flux density)
This is a vector quantity measuring the strength and direction of a magnetic field. Its direction is that in which the North pole of a freely-pivoted magnet points.
It is defined with the equation F=BIL, given the wire is perpendicular to the magnetic field.
Magnetic flux
Magnetic flux is a measurement of the total magnetic field which passes through a given area.
Magnetic Flux Linkage
Magnetic flux linkage is used when taking about magnetic flux in respect to a coil, where is shows the total magnetic flux is acting on N coils.
Faraday’s Law
When the flux linking an electrical circuit is changing, an emf is induced in the circuit of magnitude equal to the rate of change of flux linkage.
Lenz’s Law
The direction of any current resulting from an induced emf is such as to oppose the change in flux linkage that is causing the current.
Eddy Currents
Eddy currents are currents which circulate in conductors like swirling eddies in a stream. They are induced by changing magnetic fields and flow in closed loops, perpendicular to the plane of the magnetic field
