WAVES Flashcards
360’ in radians
2pi rad
1 wavelength in radians
2pi radians
Transverse wave examples
EM waves, light waves, waves on string
Longitudinal Wave Examples
Sound waves, seismic-P waves
What does a polarising filter do?
Let wave pass in one direction/ plane.
Transverse only
Aerial use
transmission and reception
Characteristics of single slit diffraction (monochromatic)
central maximum with many dimmer smaller maxima
Characteristics of double slit diffraction (monochromatic)
central maximum same size as maxima gets dimmer
Characteristics of single slit diffraction (white light)
Large central maximum, spectrum maxima, violet closest to maximum range to red furthest away
What does a single slit ensure
Ensures light of one specific wavelength, (therefore same frequency) can pass into the double slits.
How are bright fringes formed
Caused by constructive interference, occurs when superposition occurs. Phase difference has to be a multiple of 2pi rad or 0pi rad. (In phase)
Spectrometer
Shows the intensity of the light emitted (diffraction pattern)
d = a lines per mm
convert to m
1/d10^3
find total amount of orders (diffraction grating)
n = dsin(90)/wavelength
Pulse Absorption
Signal absorbed by material. Loses energy through reducing amplitude.
Countering signal degradation
Repeaters (signal booster)
Modal dispersion
Signals take different paths in a fibre. Signal will be received at different times. Results in pulse broadening. Signal may overlap. Minimise fibre used to counter this.
Material dispersion
Different wavelengths of light arriving at different times. Refractive index of fibre changes with frequency. Pulse broadens. Signals overlap. Monochromatic light used to counter this.
Appearance of visible line emission spectrum using diffraction
coloured lines, dark background
Particle behaviour of electron beam
randomly scattered, small spots of light
Wave behaviour of electron beam
Through diffraction and interference. Bright rings occur when constructive interference is taking place
mew in terms of density and area
density x area
if frequency is proportional to square root of tension, explain how frequency produced from actual experiment is different from predictions.
L and mew (mass per unit length) has to be constant. If tension is too great, string will stretch, therefore lower mass per unit length. Therefore frequency will be greater.
blue light and red light optics
blue undergoes TIR, Red will refract. Critical angle for red is more and less for blue.
blue light and red light refractive index
blue highest n, refracts more than red (smallest n)
TIR
when angle of incidence is greater than critical angle
cladding refractive index
n(cladding)<n(core)
lines per mm to grating space (m)
x1000, reciprocal
relationship between n and wavelength
n inversely proportional to wavelength
dsin(0)=n(wavelength)
Why is it important to align the aerial of a TV to receive strongest signal? (EM waves)
Similar in nature to transverse waves, which can be polarised. Aerial must be aligned in the same plane of wave.
Rarefactions and Compressions
R - regions of decreased pressure
C - regions of increased pressure
Path difference
n x wavelength
(n is an integer)
pd is a multiple of the wavelength
path difference + phase difference of destructive interference
Path d - (n + 1/2) wavelength
Phase d - 180 degree, anti phase
