IB Physics HL Topic 4- Waves

Simple harmonic motion

periodic motion where the acceleration is proportional to displacement and always directed towards equilibrium

omega

angular velocity

Huygens' principle

if the gap is between the size of one and two wavelengths all but one point source is removed and the waves diffract in a circular pattern

destructive interference

Addition of two waves when the crest of one overlaps the trough of another, so that their individual effects cancel each other. The result is a wave of decreased amplitude.

constructive interference

Addition of two waves when the crest of one overlaps the crest of another, so that their individual effects add together. The result is a wave of increased amplitude.

Thin film interference

light will hit, part reflect, reflected ray inverts; transmitted ray will continue erect and travel a total thickness of (lamda/2); the two waves meetup, the transmitted wave is 1/2 a wavelength late so the erect waves meet' constructive interference occurs.

coherence

two waves are coherent if they have the same frequency and constant phase difference

rarefaction

A region of low pressure of the medium in a longitudinal wave.

compression

A region of high pressure of the medium in a longitudinal wave.

superposition

when two waves of the same type cross. The vector sum of the two displacements of each wave

Resolution

the ability to distinguish two objects which are close together

Rayleigh criterion

two objects can just be resolved if the central maximum of the diffraction pattern is just formed at the other's first minimum

Optical activity

some substances can change the plane of polarisation by rotation

Malus' law

I=I0 cos^2(ß)

Polarisation

removing vibrations of all but one plane of a transverse wave

Brewster's angle

the angle at which the reflected ray is completely polarised,
the angle between the reflected and refracted ray is 90°
tan(B)=n2/n1

Snell's law

1mu2= v1/v2 = sin(ß1)/sin(ß2) =refractive index

Young's double slit experiment equation

wavelength=(slit sep * fringe width)/distance btw slit and screen

Pendulum equations

omega=sqrt(g/l)
T=2pi*sqrt(l/g)

spring equation

omega=sqrt(k/m)
T=2pi*sqrt(m/k)
F=kx

interference equations

dsinθ = mλ
for max:n=integer
min:n=odd integer/2

wave intensity

amount of energy per unit time flowing through unit area
I=P/4pid^2
I alpha a^2

critical angle

angle of incidence beyond which rays passing from a denser medium into a less dense medium, are totally internally reflected

diffraction

The bending of waves around a barrier or through an opening

refraction

A change in direction of a wave when it changes speed as it travels from one material to another.

Simple harmonic motion equations

x=xo cos(wt)
v=-xo sin(wt)
a=-xo cos(wt) w^2 =-xw^2

xmax=amplitude(xo)
vmax=-x0w
amax=-x0w^2

w=2pi/T

perfectly isochronous, constant period and amplitude

Doppler effect

A change in sound frequency caused by motion of the sound source, motion of the listener, or both.