1. Characteristics of Light

2. Electromagnetic Waves
Visible light can be separated into a spectrum.
Red through violet
Visible light is very small part of a larger spectrum, the electromagnetic wave spectrum.
All EM waves travel at the same speed, the speed of light (c).
In a vacuum, v = c = 3.00  108 m/s

3. Electromagnetic Waves

4. Waves and Rays
Huygen’s principle states that each point on a wave front acts as a source for new waves.
The diagram shows five points on the initial front sending out waves. These waves are part of the new front.

5. Waves and Rays
Huygen’s principle states that each point on a wave front acts as a source for new waves.
The diagram shows five points on the initial front sending out waves. These waves are part of the new front.

6. Brightness & Intensity
Illumination is measured in lumens (lm).
Illumination depends on the brightness of the source and the distance from the source.
Intensity is inversely proportional to the distance from the source.

7. Practice Problems
What is the wavelength from an FM radio band ( MHz)
3.40 – 2.78 m

8. Practice Problems
2. What is the frequency if the λ= 1km?
300,000 Hz

9. Practice Problems
3. What is the frequency if the λ= 1km?
300,000 Hz