Electromagnetic Radiation

1
Electromagnetic Radiation
2
Electromagnetic Waves

• Changing electric and magnetic fields can
  transmit energy across empty space
• Energy produced is electromagnetic radiation

3
Speed, Wavelength, and Frequency of EM Radiation

• c (speed of light) 3.00 x 108 m/s
• c ?f
• as wavelength increases, frequency decreases and
  vice versa

4
The Electromagnetic Spectrum

• Range of wavelengths
• Logarithmic scale because it spans such a large
  range of values

5
Radio Waves

• Radio, television, cell phones
• Transducersconvert sound into electrical signals
• FMfrequency modulated (shorter)
• AMamplitude modulated

6
Microwaves

• Telecommunicationsatellites
• Microwave oven

7
Infrared Radiation

• Thermal radiation
• Electric heater
• Infrared thermometer
• Remote control

8
Visible Light

• Eyes detect these waves
• ROYGBIV
• White lightmixture of all of the colors of the
  visible spectrum
• See color when that wavelength is reflected

9
Ultraviolet Radiation

• Sunlight
• Ozone molecules absorb most
• Water purifiers
• Sterilizing instruments

10
X Rays

• High energy
• Medicine
• Airport security

11
Gamma Rays

• Produced by nuclear reactions and by radioactive
  nuclei
• Medical uses

12
The Photoelectric Effect

• Photonsbundles of energy
• Plancks constant
• Energy of a photon is proportional to the
  frequency of the electromagnetic radiation.
  Plancks constant is that proportionality.
• h 6.626176 x 10-34 Js
• Ephoton hc/?

13
The Photoelectric Effect

• Work function
• The energy required to break an electron out of
  a metallic surfaceF
• Hf F KEe
• Photon energy (speed of light/wavelength) work
  function kinetic energy