Chapter 14 Light
14.1 Characteristics of Light
Electromagnetic spectrum: who, order/ timeframe founded; order of waves- radio, micro…
c = f
brightness
14.2 Flat Mirrors
Specular vs diffuse reflection
Reflection- incident and reflected angles
Virtual images; same distance from mirror; appear behind mirror
Ray tracing for flat mirrors
14.3 Curved Mirrors
Mirror equation
p is object distance; do
q is image distance; di
Magnification
ho is object height
hi is image height
know that a negative M is inverted; less than one is smaller; negative also means real
Concave = converging; convex = diverging
Focal point, center of curvature
Ray Tracing:
1. in parallel to principle axis; out through focal point
2. in through focal point; out parallel to principle axis
3. in and out through center of curvature (2f)
4. (know how to extend back reflected lines behind the mirror for virtual images)
Concave mirror:
Focal distance is positive (in front of the mirror)
Object beyond 2f: inverted, smaller, real, between f and 2f
Object at 2f: inverted, same size, real, at 2f
Object between f and 2f: inverted, larger, real, beyond 2f
Object at f: no image
Object between f and the mirror: upright, larger, virtual, behind the mirror
Know the trends such as: is a real image ever upright?
Convex mirror:
Object always upright, smaller, virtual, behind mirror
*focal distance is negative!! (Even if I don’t give you a negative number)
Be able to draw all of these as well as use the equations to find the number that go with them
14.4 Color and Polarization
Know how light is polarized, what it means, some applications, what happens when it is reflected
White light is composed of all the colors of the spectrum
An object looks the color it does because that is the color of light it reflects- it absorbs all other
colors of light
Primary colors of light
Red green blue- additive (all make white)
R + B = magenta
R + G = yellow
B + G = cyan
Primary colors of pigments
Magenta, yellow, cyan- subtractive (all make black)
Magenta reflects only blue and red light
Cyan reflects only blue and green light
Yellow reflects only red and green light
So… if you shine blue light on a green frog, the frog looks black because it only will reflect
green-- blue light has no green in it! If you shined cyan light on a green frog, it would look
green because there is green light to be reflected. In a room with a red bulb, the only colors you
see are red or black. In a room with a magenta bulb, you could see blue objects, red objects,
magenta objects- basically you’d see anything that reflects red or blue and everything else would
look black. With a magenta bulb, a cyan object would look blue because cyan reflects blue and
green—a magenta bulb provided the object with blue light to reflect, but it does not give the
object any green light to reflect back.
Objects can only reflect certain colors of light- if you don’t give it that color to reflect, it won’t!
The test should be an opportunity for you to try to bring your grade up- PLEASE study!!!