Radiant Energy:Light
The Propagation of Light:Scattering
Some beginning equations
Speed of a wave:
(1) 
Profile of the E-field:
(2) 
Propagation Number:
(3) 
Relationship between the Electric and Magnetic fields:
(4) 
Speed of light based on equation (4):
(5) 
Calculated speed of light with (5):
Accepted value of the speed of light:
Energy and Irradiance (Intensity):
(6) 
Energy of a photon:
(7) 
(8) 
Planck's Constant in Joules 
or
Planck's Constant in electron Volts 
Scattering
Scattering is the absorbtion and re-emission of photons.
The sky is blue, in part, because of Rayleigh scattering from air molecules in the upper atmosphere.
Reflection
The Law of Reflection:
The angle of incidence equals the angle
of reflection and the incident ray, the perpendicular to the surface
(Normal), and the reflected ray all lie in a plane, called the plane-of-incidence.
(9) 
Example 1
An observer is at table level, a distance d to the left of a flower of height h. The flower itself is a distance d to the left of a mirror, as shown in the sketch. Note that a ray of light propagating from the top of the flower to the observer's eye reflects from the mirror at a height y above the table. Find y in terms of the height of the flower, h.
Properties of Mirror Images Produced by Plane Mirrors
• A mirror image is upright, but appears reversed right to left.
• A mirror image appears to be the same distance behind the mirror that the object is in front of the mirror.
• A mirror image is the same size as the object.
Example 2
Two mirrors are placed at right angles, as shown in the diagram. An incident ray of light makes an angle of 30° with the x axis and reflects from the lower mirror. Find the angle the outgoing ray makes with the y axis after it reflects once from each mirror.
