Oscillations, Waves (Primers) and Modern Flashcards
Simple Harmonic Motion (SHM)
Simple harmonic motion is defined as a to-and-fro periodic motion of a body about an equilibrium point where its magnitude of acceleration is directly proportional to its magnitude of displacement, and acceleration is always directed towards the equilibrium position (i.e. acceleration and displacement are in opposite directions).
oscillation: amplitude, period, frequency
maximum displacement of the oscillating body; time taken for one complete oscillation; the number of complete oscillations per unit time
angular frequency
angular displacement per unit time
phase, phase difference
the fraction of a period a point completes after last passing through the reference position; the fraction of a cycle by which one oscillation is ahead or behind another.
Forced oscillation
A forced oscillation is the oscillation of a driven system which is maintained by an external periodic driver which applies a periodic driving force on the driven system continuously.
Energy is continuously supplied by the external periodic driver to the driven system) and the driven system oscillates at the driving frequency (of the external periodic driver)
Resonance
Resonance is a phenomenon exhibited by a driven system acted upon by an external periodic driver continuously, occurs when driving frequency approaches/is equal to the natural frequency of the driven system
there is maximum energy transfer from the external periodic driver to the driven system, driven system has the maximum amplitude. Driven system and external periodic driver are 90 degrees out of phase.
waves: amplitude, period, frequency
the magnitude of the maximum displacement of a wave disturbance from its equilibrium position; time taken for a particle in the wave to complete one cycle of an oscillation; the number of waves passing through a fixed point in a transmitting medium per unit time.
wavelength
Wavelength is the distance between any two adjacent points on the wave having the same phase at a given instant.
wavefront
Wavefront is a line or surface joining points of a wave that are in phase.
waves: phase difference
Phase difference is a measure, in angular form, of the fraction of a cycle by which two particles in a wave or two waves are out of step with each other.
Tranverse/Longitudinal
Transverse waves are waves in which the wave vibration is perpendicular/parallel to the direction of wave propagation/transfer of energy.
Polarisation
Polarisation means to restrict the vibrations of a transverse wave to one plane (axis).
Diffraction
Diffraction is the spreading of a wave into its geometrical shadow when it is incident on an edge of an obstacle or an aperture/opening.
Principle of Superposition
The principle of superposition states that the net displacement at a given place and time caused by two or more waves which traverse the same space and meet is the vector sum of the displacement which would have been produced by the individual waves separately at that position and instant of time.
Rayleigh criterion
The Rayleigh criterion states that the two images are just resolved when the central maximum of one diffraction pattern falls on the first minimum of the diffraction pattern.
Stationary wave
A stationary wave is formed when two progressive waves of equal amplitude, equal frequency and same speed, meet when they travel in opposite directions.
photon
A photon is a quantum (i.e. a discrete amount) of energy of electromagnetic radiation and its energy E, is given by E = hf where h is the Planck’s constant and f the frequency of the radiation.
Work function
The work function of a metal is the minimum energy to release an electron (the most energetic electron) from the surface of the emitter metal.
Threshold frequency
Threshold frequency is the minimum frequency of incident electromagnetic radiation to release an electron from the surface of the metal.
Ionisation energy
Ionisation energy is required to completely remove an electron initially in the ground state from an atom.
Excitation energy
Excitation energy is the energy required to raise an atom from its ground state to an excited state.
Ground state
Lowest energy level in an atom
Isotopes
Isotopes are atoms of the same element with the same number of protons but with different number of neutrons in their nucleus.
Mass defect
Mass defect is the difference between the sum of the mass individual nucleons that makes up the nucleus and mass of the nucleus itself.
Binding Energy
Binding energy is the minimum external energy required to completely separate all the neutrons and protons of a nucleus to infinity.
Nuclear Fission
Nuclear fission is the disintegration of a massive nucleus into smaller fragments of comparable masses with the release of a large amount of energy as the total mass of the daughter products is lower than the parent nuclei.
Nuclear Fusion
Nuclear fusion is the combining or fusing of two light nuclei to produce a heavier nucleus with the release of a large amount of energy as the nucleus formed has a lower total mass than that of the parent nuclei.
Radioactive decay
Radioactive decay is a naturally occurring, random and spontaenous process in which the nucleus of an unstable atom will spontaneously change into a different nuclear configuration by the emission of combinations of alpha particles, beta particles and* gamma radiation*.
Spontaneous
A spontaneous process is not affected by the presence of other nuclei. Also, the decay of a nucleus cannot be affected by chemical reactions or physical conditions such as temperature and pressure.
random decay
it is impossible to predict when a particular nucleus in a sample is going to decay
half-life
The half-life of a radioactive nuclide is the mean time taken for a quantity x to reduce to half its initial value where x represents either the number, activity or count rate of radioactive nuclei.
Decay constant
The decay constant represents the probability per unit time that a nucleus will undergo decay.
Activity
The activity of a radioactive source is the number of decays (or disintegrations) per unit time.
