Physics 20: Waves Cheat Sheet by dianadavis

Along the pulse, energy is stored in both elastic potential and kinetic energy
- At max displa­cement, PE is at max and KE is zero
- At equili­brium, KE is at max

The greater the amplitude, the greater the energy of the wave

Reflec­tion: When a wave reflects, it exhibits a phase change (crest -> trough or vice-v­ersa)
Refrac­tion:
Diffra­ction:
Interf­erence:

Standing Waves: when 2 wave trains with the same amplitude and wavelength move through each other, the resulting interf­ering pattern results in a standing wave, it appears to be standing still in a constance position
- The freque­ncies at which standing waves exist are the natural or fundam­ental resonant frequency

Nodes: points of complete destru­ctive interf­erence
Antinodes: points of complete constr­uctive interf­erence

Reflec­tion: straight waves "­bou­nce­" off a surface such that the outgoing angle (angle of reflec­tion) or reflection wave equal the incoming angle (angle of incidence) or incident wave

Angles are measure from the normal line (line perpen­dicular to the surface)

Wave Train: a series of waves linked together in phase (moving with identical motion)

Wave fronts are reflected by a barrier

When a wave passes from one medium to another through a boundary, the waves bends and changes direction (and speed) at the interface

If the medium on the other side is 'thicker' (n), then the wave will slow down and bend towards the normal line

Diffra­ction: waves bend around a corner or opening

The amount of diffra­ction depends on the wavelength and the size of the opening

Waves lose amplitude, not speed or frequency

Constr­uctive: "in phase" waves produce larger amplitudes
Destru­ctive: "out of phase" waves amplitudes cancel

Principle of Superp­osi­tion: the two waves "­sup­eri­mpo­se" and "­int­erf­ere­" with each other, creating a temporary waveform that is the sum of the two waves

Fo = observers frequency
Fs = emitted frequency
V = speed of sound
Vs = speed of object emitting sound

Subtract when the source is moving towards the observer
Add when the source is moving away from the observer

Stringed Resonator: a resonating instrument that is fixed at both ends

Closed­-Pipe Resonator: tube is closed at one end and open at another

In a closed­-tube, node at closed end and either node or antinode at open end.
IF antinode occurs at the open end, resonance occurs and the sound is amplified (louder).
IF a node occurs at the open end, resonance does not occur and almost no sound (hence only odd harmonics)

Open-Pipe Resonator: both ends of the tube are open