1. Let there be ...
Light

2. Click here and here to view simulations of electromagnetic waves.
Click here to explore a tutorial on the
production of e/m waves.

3. Light is radiant energy transported in photons that are guided along
Although we still commonly characterize
light as a wave, it is actually neither a
wave nor a particle. It seems to have
characteristics of both.
The modern view of the nature of
light recognizes the dual character:
Light is radiant energy transported
in photons that are guided along
their path by a wave field.

4. Light is ... This leads us to the Duality Principle:
a wave when it acts like a wave
a particle when it acts like a particle

5. Visible light is that portion of the
electromagnetic spectrum which stimulates the retina of the
human eye.
Visible spectrum
wavelengths range
from about 400 nm (violet) to 760 nm (red).
Light travels at about 3 x 108 m/s through
empty space and slightly slower through air.
Remember that for all waves, v = f.

6. Laws of Reflection First Law Second Law The angle of incidence, i, is
equal to the angle of reflection, r. n i r
Second Law
The incident and reflected rays,
and the normal, are coplanar.

7. Real Image Virtual Image Images formed by mirrors and lenses
may be classified as real or virtual.
Real Image
formed by actual rays of converging light
Virtual Image
not formed by actual rays of converging
light, but from where the rays of light
appear to come (diverging light rays)

8. Plane Mirror Images 1. virtual 2. upright 3. same size as object
Images formed by plane mirrors are always:
1. virtual
(virtual images are always behind mirrors)
2. upright
(virtual images are always upright)
3. same size as object
(if the image is larger or smaller, the mirror isn’t flat)
4. front and back are reversed
(some say “left and right”)
5. located as far behind the mirror
as the object is in front