Light and Color for the Middle
By Greg Corder
1. Reflection and mirrors
2. Refraction and lenses
3. Applications of lenses and mirrors
4. Color: light, pigments, and wavelength
7. Light the electromagnetic wave
8. Photoelectric effect
9. Nature of light: particle, wave, or both?
The Law of Reflection
• Concave mirrors converge light.
• Convex mirrors diverge light.
Light converges. This means that it comes together.
Also, the image is flipped past the focal point.
Light diverges. This means that light spreads
• Convex lenses converge light. The image is
flipped past the focal point.
• Concave lenses diverge light.
light to bend.
The shape of the lens
determines how the
Applications of lenses and mirrors
Color separates using a prism because different
colors have different wavelengths.
Red light bends the least and purple light bends
Color depends on Wavelength of Light.
Colored lights combine to appear
Colored lights add to become white.
Why then do paints add
to become black?
Answer: paints are pigments.
Pigments are chemicals which are
capable of absorbing one
or more frequency of white light.
Behaviors of light
Diffraction – a wave bends around an object
Light is a wave!
Interference: light is a wave!
light is a
The Electromagnetic Spectrum
Maxwell - (c. 1864) light is an EM wave
The photoelectric effect: light is a particle!
The puzzle of intensity vs. energy
Einstein - (1905)
– The duality theory of light
– Light has a dual nature: light is both a
particle and wave
Tillery, Physical Science.