P14 - Light Flashcards
reflection
-plan wave reflects from a flat barrier
reflected waves are
at same angle to barier as incident wave
when wavefront reaches barrier =
wavelet moving away
all parts of waefront
move at the same speed
reflected and incident rays are
same frequency, speed, wavelength
law of reflection
normal is perpendicular to mirror
- incident angle = reflected angle
-light reflected by plane mirror
specular reflection
reflection in a single direction without scattering
diffuse reflection
from a rough surface that scatters light
image formed by a plane mirror =
virtual image
-upright
-laterally inverted
virtual images are formed
at a place where light rays appear to come from after they have been reflected
real image
seen on a screen
-formed by focusing light onto a screen
refraction
change in direction of waves when they travel across a boundary
-change mediums
change of speed =
change of direction
light travels from air to glass
-bends towards normal
- smaller angle of refraction
-more dense medium
light travels from glass to air
away from the normal
-larger angle of refraction
-less dense medium
stars and lamps
- emit light that has a range of wavelengths (white light)
lasers
narrow range of wavelengths
violet to red (visible light spec)
-increases wavelength of light
colour filters
absorbs every colour of light’s wavelength except its own
-transmits its own
colour of surface depends on
pigments in surface materials + wavelengths of light the pigments absorb
pigments reflect
other wavelengths
a red book in blue light look
black
- absorbs all incident light
transparent
transmit all incident light
- travels through
- no light is absorbed
translucent
- let light pass but light is scattered/refracted
- as material has lots of internal boundaries = changes direction of rays
opaque
-absorbs all light
- reflected/scattered at the surface
