Oscillations + Wave Motion Flashcards
Simple Harmonic Motion
The motion of a particle about a fixed point such that its acceleration is proportional to its displacement from the fixed point and is always directed towards the point
Angular Frequency (w)
The rate of change of phase angle of oscillation, and is equal to the product of 2pi and its frequency
Amplitude
The magnitude of the maximum displacement of the particle from its equilibrium position
Period
The time taken to complete one oscillation
Free Oscillations
If an object is displaced from its equilibrium position and then released it oscillates at its natural frequency about the equilibrium position
Damping
The process whereby energy is removed from an oscillating system
Light damping
Light damping results in oscillations whereby the amplitude decays exponentially with time. the frequency of oscillation is slightly smaller than the undamped frequency
Heavy damping
Heavy damping results in no oscillation and the system takes a long time to return to its equilibrium position
Critical damping
Critical damping results in no oscillation and the system returns to its equilibrium position in the shortest time.
Resonance
Resonance occurs when a system responds at maximum amplitude to an external driving force. This occurs when the frequency of the driving force is equal to the natural frequency of the driven system
Malus’s Law
The intensity of a beam of plane-polarised light after passing through a polariser varies with the square of the cosine of the angle through which the polariser is rotated from the position that gives maximum intensity
I = Io(costheta)^2
Wavelength
The distance between two consecutive points which are in phase
Frequency
The number of oscillations made per unit time
Progressive wave
A wave that transports energy from one point to another in the direction of wave propagation
Transverse wave
A wave in which its particles oscillate in a direction perpendicular to the direction of energy transfer
Longitudinal wave
A wave in which its particles oscillate in a direction parallel to the direction of energy transfer
Wavefront
A line or surface joining points on a wave that are in phase. The wave travels in a direction perpendicular to these wavefronts
Phase Difference
The phase difference between to particles in a wave or between two waves at a point is a measure of the fraction of a cycle which one is ahead of the other
Inverse Square Law
If the power of the source is constant, then the intensity is inversely proportional to the square of the distance from the source.
Phase angle
An angle that gives a measure of the fraction of a cycle that has been completed by an oscillating particle or by a wave
In phase
Particles of a wave are considered in phase when they execute the same motion at the same time
Anti phase
Particles of a wave are considered to be in antiphase when they execute motions that are out of phase by pi radians or 180 degrees
Out of phase
Particles of a wave that show different stages of motion. They have non zero phase difference
