1. Introduction to light and the electromagnetic spectrum

2. What is Light??

3. What is Light? Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight.
PROPERTIES OF LIGHT:
1) Light travels at high speeds
3.0 x 108m/s
7.5 times around the Earth in 1 second!!!

4. 2) Light travels in straight lines called linear propagation
2) Light travels in straight lines called linear propagation. Evidence: shadows

5. 3) Light is a transverse wave, which means, the particles in the medium move in a direction perpendicular to the direction of propagation.

6. Light – An Electromagnetic Wave
Light is a form of energy that radiates as an ELECTROMAGNETIC WAVE
Does not require a medium
EM waves include:
Radio waves, x-rays, microwaves, radar, UV light, etc.
VISIBLE LIGHT are EM waves that the human eye can detect

8. The wave equation

9. Light – An Electromagnetic Wave

10. Electromagnetic Spectrum
The ELECTROMAGNETIC SPECTRUM classifies EM waves by energy from waves with the longest wavelength to the shortest

12. EM Waves in Our Society

13. Radio Waves Longest wavelength and lowest frequency USES: AM/FM radio,
TV broadcasts,
cell phones,
radar,

14. Microwaves Shorter wavelength and higher frequency than radio waves
Therefore, they carry more energy
USES:
Microwave ovens (heats food making water particles in food vibrate)
Telecommunication

15. http://www. youtube. com/watch. v=jgjx4JROjR4 http://www. youtube

16. Infrared Light Wavelength is still longer than visible light USES:
Remote controls
Lasers
Heat detection and remote sensing
Keeps food warm
Physical therapy

17. Visible Light Can be detected by the human eye USES: Human vision
Lighting
Rainbows
Visible lasers

18. Visible Light
White visible light is composed of a continuous sequence of colours called the VISIBLE SPECTRUM
ROYGBIV: red, orange, yellow, green, blue, indigo, violet

19. Ultraviolet Light
Carries more energy than visible light, with a shorter wavelength and higher frequency
USES:
Tans skin and causes sunburn
Increases risk of skin cancer
Stimulates vitamin D production
Sterilization and disinfection
“black” lights

20. X-Rays Shorter than UV rays USES: Medical imaging Security equipment
Cancer treatment

21. Gamma Rays Highest frequency and shortest wavelength USES:
Cancer treatment

22. Prisms
Isaac Newton separated white light into the visible spectrum using a triangular prism
The prism slows down the speed of light
Red light (least energetic) is slowed the least
Violet (most energetic) is slowed the most