waves Flashcards
how to get total internal refraction
if I is bigger than critical angle you get total internal reflection means no refraction
what happens if Incident ray equals critical angle
refraction occurs along the boundary
what happens if incident angle is less than critical angle
both reflection and refraction
equation for critical angle
sin c = incident angle/refractive index
what is refractive index
how much a medium alters the speed of light
what are convex (convering) lens
lens making parallel rays coverage principal focus e.g magnifying glass
concave (diverging) lens
lens makes parallel rays diverge (spread out) e.g in glasses
focal length
the distance between the center of a lens
and its point of focus
principal focus
the point where parallel rays meet after they pass through a lens
monochromatic
name for the light of a single frequency
how does a prism disperse light
prism sides not parallel , light refracted
- prism refracts each color by a different amount
- light splits into range of colors (spectrum)
color spectrum
order = red, orange, yellow, green, blue, indigo, violet
red light slowed down least - refracted least
violet light slowed
down most - refracted most
radio waves
broadcasting, communication
microwaves
satellite communication, cooking
infra-red
communication (remote controls), cooking
visible
viewing objects, optical fibers
uv
tanning beds, fluorescent light
x rays
imaging in medicine, viewing the internal structure of objects
gamma rays
kill cancer cells, sterilize surgical equipment
dangers from wavelength
infrared - cause skin burns
uv - causes skin cancer
reducing dangers from wavelength
uv - wear sunscreens sun glasses
xray exposure - limit exposure time , wear protective clothing
satelittes
200-1000km above the earth
satellite phone + tv
orbit earth at the same speed the earth is rotating
microwaves advantages
long wavelength,
can penetrate walls,
require short anial for transmission and reception
optical fibres
- visible light
- carry high rates of data
electricity signals
digital - 2 values on or off 1 or 0
analog signals - varies in terms of frequency and amplitude
explanation why digital signals are better quality
due to on or off signals, noise can easily be removed
- regeneration
- quality maintained
- more information per second
echo
reflected sound wave = s=d/1/2t
how do longitudinal waves diff from transverse
vibrations OR compressions AND rarefactions
vibrations parallel to direction of travel (of wave energy)
longitudinal waves and transverse for direction
longitudinal - in direction of wave
transverse - perpendicular
