Light

1
Light

• Electromagnetic Radiation
• EM Radiation
• EM Spectrum
• Types of EM Radiation

2
EM Radiation

• Electromagnetic Radiation
• transverse waves produced by the motion of
  electrically charged particles
• does not require a medium
• speed in a vacuum 3.00 x 108 m/s (c)
• electric and magnetic components are
  perpendicular
• c ? (wavelength) . v (frequency)

3
Speed of Light Problems

• Ex. A station broadcasts a radio wave with a
  wavelength of 3.0 m. What is the frequency of
  the wave?

GIVEN
WORK
? 3.0 m v ? c 3.00 x 108 m/s
v c ? v 3.00 x 108 m/s 3.0 m v 1.0 x
108 Hz
4
EM Radiation

• Photons
• tiny, particle-like bundles of radiation
• absorbed and released by electrons

• energy increases with wave frequency

5
EM Spectrum
long ? low f low energy
short ? high f high energy
6
Types of EM Radiation

• Radio waves
• lowest energy EM radiation

7
Types of EM Radiation

• Radio waves
• FM - frequency modulation
• AM - amplitude modulation

• Microwaves
• penetrate food and vibrate water fat molecules
  to produce thermal energy

8
Types of EM Radiation

• Infrared Radiation (IR)
• slightly lower energy than visible light
• can raise the thermal energy of objects
• thermogram - image made by detecting IR radiation

9
Types of EM Radiation

• Visible Light
• small part of the spectrum we can see
• ROY G. BIV - colors in order of increasing
  energy

10
Types of EM Radiation

• Ultraviolet Radiation (UV)
• slightly higher energy than visible light
• Types
• UVA - tanning, wrinkles
• UVB - sunburn, cancer
• UVC - most harmful, sterilization

11
Types of EM Radiation

• Ultraviolet Radiation (UV)
• Ozone layer depletion UV exposure!

12
Types of EM Radiation

• X rays
• higher energy than UV
• can penetrate soft tissue, but not bones

13
Types of EM Radiation

• Gamma rays
• highest energy EM radiation
• emitted by radioactive atoms
• used to kill cancerous cells