Waves Flashcards
refraction
light changing speed and direction towards the normal as it enters a new medium
total internal reflection (requirements)
must go from more -> less dense refractive index. the critical angle must be smaller than the angle of incidence, causing reflection to occur
n1sin01
0 = sin-1(n1sin01/n2)
waves moving from deep -> shallow
AS DEPTH DECREASES
amplitude increases, more friction so velocity decreases, wavelength decreases, frequency is constant as it is dependant on energy.
sound waves
need to travel through medium, slower than light waves, longitudinal/mechanical, longer wavelength than light rays
light waves
do not need to travel through medium, fast, electromagnetic/transverse, shorter wavelength than sound waves
loud/bright/tall wave
constructive interference, crests meet crests or troughs meet troughs, waves are in phase producing an anti-node, path difference = 0 or n = 1,2 (connect to diffraction)
quiet/dim/short wave
deconstructive interference, crests meet troughs, waves are out of phase producing a node, path difference n = 1,2 + 1/2 (connect to diffraction)
concave mirror
small field of view & you can only see a small range of images, images appear inverted if outside focal length, images are real, images are diminished
How do we know if the image is real?
Reflected rays will meet at a point.
When is there no image?
Object is at F
What is the critical angle?
The angle beyond which light is totally internally reflected (T.I.R)
convex mirror
wide field of view, images are virtual, cannot be used for magnifying
How do fibre optic cables work?
Light travels through water due to total internal reflection.
long wavelength small opening
waves with long wavelengths going through openings smaller than their wavelength causes the waves to diffract outwards/spread out.
small wavelength big opening
smaller waves do not diffract and will pass on through the opening as normal then round off at the sides
increasing curvature
increases focal length, so image forms further away from mirror
refractive index
an index comparing the ratio of velocity of light to velocity in a specific medium, has no units
concave mirror image at focal point
no image as the distance of the image is at an infinite length.
In phase
Particles moving with the same velocity and the same displacement (in sync)
The spreading of waves as they pass through a gap (aperture) or around an obstacle.
Diffraction
If the wavelength is greater than the gap size,
There is maximum diffraction
If the wavelength is smaller than the gap size,
There is minimum diffraction
how refraction works (water)
light exiting medium to speed up and hits boundary at an angle, change in speed causes change in direction. eye assumes light cannot bend and sees object closer/shallower than it is (trace back in straight line)
