1. Electromagnetic Radiation
Optics – Part I
Electromagnetic Radiation

2. Charged Particles Static (still) charges Moving charges
electric field
Moving charges
magnetic field
Accelerating charges
electromagnetic waves

3. Electromagnetic Waves
Also called electromagnetic radiation
radiate away from the accelerating charge
properties of electromagnetic waves are characterized by Maxwell’s Equations

4. Maxwell’s Equations Gauss’s Law Gauss’s Law for Magnetism
electric field lines start and stop on electric charges
Gauss’s Law for Magnetism
magnetic field lines always make closed loop
Faraday’s Law
changing magnetic fields are a source of electric fields
Ampere-Maxwell Law
changing electric fields are a source of magnetic fields

5. Properties of EM Waves peak trough wavelength frequency
the highest part of a wave
trough
the lowest part of a wave
wavelength
distance from one peak to the next
frequency
number of waves that pass a given point in one second (measured in Hz)

6. EM waves can exist an any
frequency
wavelength
The properties of EM waves and their interactions with matter depend on the wavelength of the wave.

7. Electromagnetic Spectrum
The range of wavelengths of EM waves is called the electromagnetic spectrum.

8. Electromagnetic Spectrum
Divided according to wavelength
radio waves
microwaves
infrared waves
visible light
ultraviolet rays
x-rays
gamma rays
longer
shorter

9. Radio waves longest wavelength
radio and television stations are assigned bands within the radio wave spectrum to broadcast in
each station broadcasts their station on a slightly different wavelength

10. Microwaves used in communication radar microwave ovens cell phones
satellite tv
radar
microwave ovens
The wavelength of the waves inside your microwave are about 12 cm.

11. Infrared Waves
also called thermal radiation because it is associated with heat
wavelengths range from 1 millimeter to 1 nanometer

12. Visible Light
part of the spectrum that can be detected by the human eye.
ranges from 700 nanometers (red) to 400 nanometers (blue)

13. Visible Light
Light that contains a mixture of all the wavelengths appears white
White light can be separated into colors using prisms.

14. Types of Visible Light Some objects are a source of light.
light bulbs
sun
fire flies
Most objects we see are not sources of light; we see them because they reflect light.
tables
walls
people

15. Reflected Light When light hits an object
some wavelengths are absorbed by the object
some wavelengths are reflected by the object
We see a lemon as yellow because
it reflects yellow light
and absorbs all other colors

16. Reflected Light White objects reflect all wavelengths
Black objects absorb all wavelengths

17. Ultra-Violet Rays UV Rays range from 10 – 400 nanometers
harmful to humans because they are small enough to pass through the pores of our skin
Fluorescent materials absorb UV light and then emit visible light.

18. X-Rays and Gamma Rays shortest wavelength of all rays
carries large amounts of energy
A gamma ray burst can emit more energy in 10 seconds than the sun can in its entire life.

19. Traveling Light Light does not need a medium through which to travel.
Speed of light in air = 3 x 108 m/s
As light passes from one material to another, the light may change speeds.

20. Bending Light
When light passes from one material to another, the light is bent.
The index of refraction refers to the bending of a wave as it passes from one medium to another.
When changing mediums, the wavelength may change but the frequency remains constant.

21. Intensity and Polarization
amount of energy that reaches a given area in a given amount of time
Polarization
orientation of the wave
light can be polarized because it is a transverse wave

22. Polarization Linearly Polarized Light Polarized along horizontal
vertical

23. Doppler Effect refers to the appearance of a wave
wavelength appears different to a moving observer than a still observer
blue shift
light appears to have a shorter wavelength
red shift
light appears to have a longer wavelength
only occurs when objects are moving VERY fast (in outer space)

24. Doppler Effect
used to measure the speed of stars