Nature of Light

1
Nature of Light
2
Light

• Light can be modeled as a wave and a particle
• Transverse, electromagnetic wave
• Photons particles of light

3
Speed of Light

• Vacuum 3.00 x 108 m/s
• Water 2.25 x 108 m/s
• Glass 1.97 x 108 m/s
• Generally decreases as medium increases in
  density.

4
Intensity

• Intensity is referred to as brightness.
• Intensity decreases as distance from the origin
  increases. Why?
• Photons spread out over wider area.

5
Lasers

• A device that controls the way energized atoms
  release photons.
• The word originates from the phrase light
  amplification by stimulated emission of radiation.

6
Properties of Lasers

• Monochromatic one specific color
• Coherent organized moves in step with others
• Directional tight beam strong and concentrated

7
Modeling With Rays

• Rough surfaces reflect at all angles. This is
  called diffuse reflection.
• Smooth surfaces reflect light rays in one
  direction. This is called specular reflection.

8
Modeling with Light Rays

• The angle at which the ray strikes the surface is
  called the angle of incidence.
• The angle at which the light is reflected is
  called the angle of reflection.

9
Law of Reflection

• The angle of incidence is equal to the angle of
  reflection.
• Both are measured from a line perpendicular to
  the surface called the normal.

10
Mirrors

• As light reflects off a mirror, some rays hit
  your eye and your brain interprets this as an
  image behind the mirror.

11
Flat Mirrors

• Show a virtual image, located behind the mirror
  at the same distance as the object is from the
  surface.
• Ex Bathroom Mirror

12
Concave Mirrors

• Used to focus reflected light (magnification)
• Can create a real image in front of the mirror.
• Ex reflecting telescopes

13
Convex Mirrors

• Used to gather more images.
• Ex Mirror in corner of store or on side of car
  (objects in the mirror are closer than they
  appear). Let you see around a corner.