Waves Flashcards
speed of light
c = 3 x 10^8 m/s
speed of sound
343 m/s
wavelength frequency speed
v = fλ
frequency, time period
T = 1/f
Polarization
waves of the transverse waves are limited to one plane of movement, while the rest is absorbed
polarising filters what they do
only waves oscillating in same direction as filter will pass through
2 filters perpendicular to each other won’t let through any light
uses of polarisation
- polarised sunglasses to reduce glare
- receiving areal and radio signals
stationary waves nodes and antinodes
node - no displacement
anti-node - point of max displacement
distance between two nodes
1/2 λ
Explain how standing wave is formed (3)
- superposition
- two waves of same frequency and amplitude
- travelling in opposite directions
- one is reflected
points between two nodes
points between two nodes all in phase
For first harmonic:
frequency, length, tension, μ
For first harmonic:
f = 1/2L sqrt(T/μ)
where μ is mass/length of string
standing wave with microwave practical setup
transmitter
metallic reflective plate 1/2λ away
movable detector in middle
when detector is at plate, min
when at middle, max
standing wave in a tube
at closed end: pressure antinode, displacement node
at open end: pressure node, displacement antinode
laser
monochromatic light (one wavelength) so light is coherent
double slit setup and result
laser which has similar wavelength to gap
result is equally spaces fringes
single slit diffraction monochromatic
large central maxima with smaller less intense fringes on either side
single slit diffraction white light
- central maxima bright white
- less wide less intense fringes on either side
- fringes on either side would be spectrum which get more and more spread out
- violet closest to maxima, red furthest
diffraction
the spreading out of waves as they pass through a gap or around an obstruction
single slit equation (destructive min)
dsin(θ) = mλ
where d is the slit width
m is the order of the min
double slit equation
W = λD/s
where w is fringe spacing
D is from slits to screen
s is slit spacing
diffraction grating equation and derivation
dsin(θ) = nλ
where d is the slit width
n is the order of the bright spot
derive on paper
snells law
n1sin(θ1) = n2sin( θ2)
refractive index, speed of light
n = c in air/ c in material