1. Light

2. Electromagnetic waves
Do not require a medium
consist of both an electric and a magnetic component
Electromagnetic wave

3. Electromagnetic Spectrum
All EM waves move at the same speed: c = 299,792,458 m/s or 3.0 x 108 m/s
Shorter wavelengths have higher energy.
Longer wavelengths have lower energy.
EM Spectrum song

4. Light Intensity Another Inverse square rule:
Intensity varies inversely with square of distance from source
Surface area of sphere = ???

5. Questions 1) What is the frequency of violet light?
2) What color is light with a frequency of 4×1014 Hz?
3) Suppose you travel to Uranus which is 19 times as far away from the sun as the Earth. What would the brightness of the sun look like to you?

6. Light acts like a wave
Light behaves in a way that is consistent with our conceptual and mathematical understanding of waves.
Light reflects when it hits an obstacle.
Light refracts when it moves from one medium to another.

7. Diffraction & Interference
Light undergoes diffraction when it passes through an opening or moves around a barrier.
Light waves display interference.

8. Light exhibits the Doppler Effect: light from stars moving towards the Earth display “blue shift” and light from stars moving away display “red shift”
What is redshift?
Light can be polarized. Polarized light has waves that all vibrate in the same direction. Reflected light is often polarized.
Polarized light

9. Thin film interference
Interference of light waves reflecting off the top surface of a film with the waves reflecting from the bottom surface.
To obtain a nice colored pattern, the thickness of the film has to be similar to the wavelength of light.
Soap bubble