Chapter 14 - Light

1
Chapter 14 - Light

• Electromagnetic Wave- a wave that consists of
  vibrating electric and magnetic fields that
  radiate outward from the source at the speed of
  light.
• Speed of Light (c) c3.00 x 108 m/s
• Electromagnetic Spectrum- from least frequency to
  greatest- Radio Waves, Microwaves, Infrared,
  Visible Light, Ultraviolet, X-rays, Gamma Rays

2

• Radio Waves AM FM radio, Television
  broadcasts l gt 30 cm, f lt 109 hz
• Microwaves- radar, aircraft navigation, microwave
  ovens, research
• 30 cmgtlgt1 mm, E 9 hzltflt 3 E11 hz
• Infrared- physical therapy, infrared photography,
  molecular spectra
• 1 mmgtlgt700 nm, 3 E11 hzltflt4.3 E14 hz
• Visible Light- 700 nm(red)gtlgt400 nm(violet)
• 4.3 E14 hzlt f lt 7.5 E14 hz

3

• Ultraviolet- sterilize medical instruments,
  identify fluorescent minerals, sunburn
• 400 nmgtlgt60 nm,
• 7.5 E14 hzlt f lt 5 E15 hz
• X-rays- medical exam of bones, teeth and organs,
  treatment for types of cancer
• 60 nmgtlgt 1E-4 nm
• 5 E15 hz lt f lt 3 E21 hz
• Gamma Rays- treatment for cancer, food
  irradiation, exam for structural flaws

4

• Wave speed equation for light c f l
• Two basic theories of light- Wave Theory,
  Particle Theory. Light acts like both at
  different times.
• Wave Theory- has a wavelength, frequency, starts
  with a vibration, can have interference
  (constructive and destructive), polarization
• Particle Theory- reflection, refraction, ray
  diagrams

5

• Law of Reflection- the angle at which light
  strikes a surface with respect to the Normal
  (perpendicular line to the surface), is equal to
  the angle at which light leaves the surface.
• Angle of incidence Angle of reflection
• Diffuse reflection- the reflection off of a rough
  surface no glare
• Specular reflection- smooth surfaces, such as
  glass and water.

6
Flat Mirrors

• Virtual image is formed, that appears to be
  behind the mirror at the same distance as the
  object in front of the mirror.
• Images will be the same size as the object.
• The image formed is reverse of the object.