1. A guide to Electromagnetic Waves
Light
A guide to
Electromagnetic Waves

2. Electromagnetic Radiation
Electromagnetic waves are transverse waves made from electrically charged particles.
Transfer of energy by these waves is called radiation.
No need for a medium
Travel through a vacuum or empty space
Light from the stars is one example

3. Electromagnetic Waves
Electromagnetic waves are arranged on the electromagnetic spectrum by their wavelength and frequency.
Low-frequency, long wavelength---Radio waves
High-frequency, short wavelength--- gamma rays

4. Photons Radiation carries energy and has momentum.
Scientists believe that electromagnetic radiation may act like
particles as well as like waves!
Albert Einstein, in 1905 hypothesized that light is composed of tiny particles.
He called these tiny bundles of radiation PHOTONS!

5. Electromagnetic Spectrum
All electromagnetic waves are classified by their wavelength and their frequency on the electromagnetic spectrum.

6. Radio Waves
Long wavelength, low frequency
Low photon energy
Used in Communication and Cooking:
Radios, TV’s, Cellular Phones, Cordless phones
Modulation- the process of varying the amplitude or frequency of radio waves by
Voice, music, video, computer information
Highest frequency radio waves are called microwaves.
Used in cooking and communication
Radar is used to detect the echoes of radio waves from distant objects.

7. Infrared Radiation Infrared radiation indicates the presence of heat.
Wavelength is slightly longer than that of visible light.
Warm objects give off infrared radiation.
Sunlight, body heat, infrared lamps are all examples of Infrared radiation.

8. Visible Radiation
The only part of the electromagnetic Spectrum you can see!
Small range on the spectrum compared to the other types of radiation.
Visible light can cause chemical reactions to take place.

9. Ultraviolet Radiation
Higher frequency than visible light
Photons more energetic
Ozone layer blocks most of the ultraviolet radiation from the sun.
Help the skin to produce Vitamin D
Used to kill bacteria and viruses
Too much causes skin cancer

10. X-Rays and Gamma Rays X-rays: Gamma Rays
Shorter wavelengths and higher frequencies than ultraviolet radiation.
Photons have higher energy and carry more penetrating power.
Passes through some materials and absorbed by others.
Used to Scan luggage at airport
Gamma Rays
Highest frequency
Most penetrating
Emitted from the nuclei of radioactive atoms
Can kill cancer cells

11. Sheer curtains, frosted glass, waxed paper
Light
The type of material determines the amount of light it absorbs or reflects
Opaque materials absorb or reflect light so you cannot see through them.
Heavy dark curtains on a window
Transparent materials allow light to pass through, you can see clearly through them
Glass windows
Translucent materials allow some light to pass through, but you cannot see through them clearly
Sheer curtains, frosted glass, waxed paper

12. Color
White light is made up of the colors of the spectrum.

13. How you see the colors of light
An object appears to be a certain color because that is the color of the light spectrum it reflects.
An object appears white because it reflects all the colors of the light spectrum.
An object appears black because it absorbs all the colors of the light spectrum and reflects little or no light.

14. How colors of light are seen
Primary Colors of light
Red Green Blue
Photoreceptors
1.Cones: 3 Types
A. Red Cones Absorb Red and Yellow Light
B. Green Cones Absorb Yellow and Green Light
C. Blue Cones Absorb Blue and Violet Light
2. Rods:
Sensitive to dim light and are used for night vision

15. Color---Seeing the light
Check your vision for color blindness.
8% of men, .5% of women suffer.
What numbers do you see??
An inherited condition where cones malfunction.

16. Pigments
A pigment is a material that absorbs some colors and reflects others.
Used by artists to make colors of paint.
Three primary pigments
Cyan, magenta,yellow
Color of pigment depends on the light it reflects

17. Battle of the Bulbs Incandescent Lighting Fluorescent Lighting
Thin wire of tungsten (W)
Gets very hot!
Gives off light
80% of the energy given off is heat.
Fluorescent Lighting
Filled with gas, Argon
Coated with phosphors
Give off visible light when they absorb UV radiation.
No excessive heat given off
Use 1/5 the electricity
Last longer
Can confuse your TV and VCR