Waves & Optics Flashcards
what are features of longitudinal waves
- move in one direction
- compressions and rarefactions
- same plane
what are features of transverse waves
- particles oscillate up & down
- also eventually going in the same direction
- amplitude is an abs number of the deviation of one wave from the midpoint (halfway between the min & max)
what does lambda represent
wavelength (width of the wave)
what is frequency is this context
number of waveslengths passing through per one point in one second measured in Hz
what is the formula for frequency
f = 1/T * lambda
what is the formula for velocity of a wave
v = f*lambda (wavelength)
e.g. m/s = m per sec
what is a photon
a massless packet of light energy (m=0) with a lot of wave properties
where does light reflect off
a surface
what is the angle of incidence
notes
angle against the normal path of light
what is the angle of reflection
notes
angle that results from light bending into another medium
give an example of refraction
light going from one gas to another, from the air to the ocean
what is the optical density of air
1.0
when is thetar > thetai
n2 < n1 e.g. going from more optically dense to less optically dense
when is thetai < thetar
n2 < n1 e.g. going from less optically dense to more optically dense
what is snell’s law
n1sin(theta1) = n2sin(thetar)
what is sin(30)
0.5
what is sin(theta)
oppsite/hypotenuse
what is >sin(30)
> 0.5
what is sin(0)
0
what is diffraction
where light acts as a wave rather than a particle
what is destructive interference
where two waves of light are the same so they cancel each other out and light = 0
what is constructive interference
points where the waves have cross hairs (notes)
what is the formula for energy of a photon
E = hc/lambda = hf
where h = constant, c = speed of light, lambda = wavelength
what is energy of photons measured in
Joules or electron volts (EV)
how does a convex lens impact light (draw it)
it bends it inwards toward the axis
how does a concave lens treat light
it diverges it, e.g. away from the axis for the focal length (f)
what is the thin lens formula
1/f = 1/u + 1/v
where f = focal length, v = image position & u = object position
what are the features of an image projected from a convex lens
- magnified
- inverted
- real
what are the features of an image projected from a concave lens
- upright
- minimised
- virtual
