1. Electromagnetic Spectrum

2. How are colors of visible light different?
What makes red light look red? Or blue look blue?
The wavelength determines what color we see
Red has the longest wavelength of visible light
Violet has the shortest wavelength of visible light

3. Vocabulary Help Page
Wavelength – The distance from crest to crest of a wave. How long the wave is in meters.
Frequency – The number of waves that pass a point in one second. Determines the energy a wave has. Measured in Hertz.

4. The Electromagnetic Spectrum
Electromagnetic Spectrum—Consists of waves at all possible energies, frequencies, and wavelengths. They are placed in order of increasing frequency
So what do we notice about the wave as we move further right on our diagram?

5. Radio Waves
Radio waves have the longest wavelengths and lowest frequency in the electromagnetic spectrum.
Cellular phones also use radio waves to transmit information. These waves are much smaller than TV and FM radio waves.

6. Microwaves
A microwave oven works by passing microwave radiation, through the food.
The energy causes the food particles to vibrate against each other.
What’s the by product of things rubbing together???

7. Infrared Light (below red)
IR light from the sun is what keeps you warm
Uses: remote controls, the bottom of your mouse, night vision, target acquisition and tracking by the military and short- ranged wireless communication.

8. Visible Light
The portion of the spectrum which can be detected by the human eye.
Some colors like brown, pink, and magenta are not present, but are a blend of different wavelengths.
violet
380–450 nm
blue
450–495 nm
green
495–570 nm
yellow
570–590 nm
orange
590–620 nm
red
620–750 nm

9. Ultraviolet (beyond violet)
UV Light carries more energy than visible light
Because of absorption in the atmosphere’s ozone layer, more harmful types of UV light is blocked.
This type of wave is what causes your skin to tan and burn.
Used in tanning beds and black lights
Too much can cause skin cancer.
Some birds (birds of prey) and bees can see in the UV light spectrum
Used to kill bacteria. (Sterilization of equipment)
Causes your skin to produce vitamin D
(good for teeth and bones in moderation)
Use sun block to protect against (UV rays)
UV rays are also what cause “sun bleaching”
when certain materials are left outside

10. X-Rays
Waves longer than gamma, shorter than ultraviolet. Widely used in medical imaging.
Carry a great deal of energy
Has enough energy to pass the less dense tissues but not bone.
Teeth and Bones absorb x-rays
Too much exposure can cause cancer

11. Gamma Rays
Smallest Wavelength (Highest Frequency) = MOST ENERGY of entire EMS
Gamma rays are the most dangerous form of radiation emitted by a nuclear explosion
Due to their high energy content, they are able to cause serious damage when absorbed by living cells.
Naturally occur in:
Radioisotopes on Earth
(Radium, carbon-14, uranium-235, etc)
Fission and fusion reactions
produce it
Sun spots (most all of radiation
absorbed by atmosphere)

13. What type of electromagnetic waves have the most energy?
What type has the longest wavelength?
What type has the highest frequency?
What visible light has the longest wavelength?
What visible light has the lowest frequency?

14. Light sabre demo/discussion- last chance if not done yet.