reflection - an object that reflects light when it hits it.
a more dense medium has a higher concentration of particles per unit volume than a less dense medium. light will be as close as possible to the normal line
opaque - can't see through it, eg. paper - is very reflective
concave lens - bend backwards. can't make a real image because the rays are diverging
convex lens - bend inwards
transparent - see through eg, window
transmit (through a surface) - carry on through
absorbed - energy stops being a wave and converts into something else
white light from the sun has all the colours, but we can only see red, blue and green. because our cone cells can only detect red, blue and green. all the other colours are made from these three
Yellow - red + green
Magneta - blue + red
Cuan - green + blue
Refraction
Waves travel through a medium or material
Waves that can travel through a medium
Light waves
Air
Water
Any other transparent material
Refraction
When a wave goes from traveling in one medium to another, refraction occurs
Refraction is a change in speed and direction of the wave
Water waves go from deep to shallow water
They slow down
Water waves go from shallow to deep water
They speed up
Wave properties and refraction
Frequency does not change
Wavelength and speed can change
Direction of travel can change
Optical density
Transparent materials have different opticaldensity from each other
Light waves travel in a medium
They travel more slowly in a denser medium and faster in a less dense medium
In emptyspace the speed of light is 3.00x10^8 m/s
Change in speed of light
Causes the direction of the wave to change compared to the normal line
Light Refraction rules
1. If light travels from less dense to more dense medium:
2. Slow down
3. Change direction toward the normal line
4. If light travels from more dense to less dense medium:
5. Increase speed
6. Change direction away from the normal line
Luminosity
Luminous objects produce their own light, which radiates away in all directions
Luminosity
The glow can be a result of being high temperature, or due to energy released in a chemical reaction
Reflectivity
Reflective objects appear when light from another source shines upon them
All visible non-luminous objects are at least a little bit reflective
Reflectivity
The more reflective, the brighter they appear
Ray diagrams
Rays represent the path a single light wave takes after it is emitted until it is absorbed
Ray diagrams
The ray is shown as a straight line with an arrowhead showing the direction of the light's motion
Rays always start from luminous objects, but they can bounce off reflective objects along the way
Law of reflection
angle of incidence = the angle of reflection
Formation of an image
Multiple rays reaching the eye from slightly different directions allow the eye to see the shape and size of objects in the field of view
Real image
If the rays come directly from the object seen
Virtual image
If the rays' direction is changed along the way
Specular reflection
Smooth flat planar surface are able to reflect multiple rays at once, so that parallel incident rays become parallel reflected rays
Specular reflection
The parallel rays will produce a clear image for the observer
Diffuse reflection
Rough surfaces reflect all the same rays, but the rays which became parallel will not be parallel upon reflecting
Diffuse reflection
The nonparallel rays will carry light but no clear image