This document discusses the nature of light. It begins by asking questions about whether light is a wave or particle and how it is produced and travels. It then provides information about light, such as its speed, ability to carry energy and information, and travel in straight lines. The document explains that light is both a wave and particle, with photons as the particle. It discusses the electromagnetic spectrum and how light waves carry energy related to their wavelength. Light is produced through electron excitation in atoms. The full spectrum is described, from radio to gamma rays.

1. What is Light?
What are some examples of light?

2. Questions about Light
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Is it a wave or a particle?
How is light produced?
How is color determined?
How does it travel through empty space?
How fast does it travel?
How does light bend, reflect, and spread
out?

3. LIGHT
• Light travels extremely fast and over long
distances
• Light carries energy and information
• Light travels in straight lines
• Light has color
• Light has different intensities/energy.

4. Light is both a WAVE and a
PARTICLE!
Photon: a bundle of light with a certain
amount of energy.

5. Light travels in
waves but it is made
of tiny particles
called photons.

6. What is a wave?
A disturbance which carries
energy through space

7. The amount of energy a light wave
carries is related to its wavelength,
which is the distance between two
identical points.

8. Long wavelength = low energy = red
Short wavelength = higher energy = violet
ROYGBIV

9. A sound wave is an oscillation
(vibration) of air.
A water wave is an oscillation
(vibration) of the surface of the
water.
What is oscillating in a light wave?
The answer is electricity and
magnetism!

10. How is Light Produced?
When an electron is energized, it
moves up to a higher energy level,
then falls back down releasing a
photon with a certain amount of energy!

12. The Electromagnetic Spectrum
includes different types of waves
arranged in order of their
wavelength and frequency. There
are 7 different types of
electromagnetic waves in the
spectrum.

13. All Electromagnetic Waves
• Carry energy in proportion to their
wavelength (long wavelength = low energy)
• Are created by the motion of electric
charges (electrons in atoms!!)
• Can travel through a vacuum, at the speed
of c = 3.0 x 108 m/s (300,000,000 m/s)
• Are forms of “light”

15. QuickTime™ and a
decompressor
http://www.google.com/imgres?um=1&
are needed to see this picture.
US:official&authuser=0&biw=598&bi
new.jpg/500px-EM_Spectrum3-new.jp

17. Longest
wavelength:
0.1 to 10,000 m
-communication
-telescopes
-broadcasting

18. Wavelengths of centimeters
Used in weather forecasting (radar)

19. = heat radiation

20. Visible Light
Is really only a very small part of the entire spectrum!
ROYGBIV

21. Ultraviolet (UV) light has shorter wavelengths than visible light. Though these waves are invisible to the human eye, some
insects, like bumblebees, can see them!
Can be seen by some insects, but not humans.
Causes suntan and sunburn
Used to sterilize medical equipment
Has higher energy than visible light

22. Discovered by Wilhelm Roentgen, 1895

23. Gamma rays
Gamma rays have the shortest
wavelengths. They are given off by
radioactive materials. They can
pass through soft materials easily,
but are stopped by metals. Used for
medical and agriculture reasons,
as well as for safety and security!
λ less than .000000000001 meters