1. CHAPTER 3: Light

2. In 1860, James Clerk Maxwell combined and unified the current theories of electricity and magnetism and showed that electric and magnetic fields should travel through space together in the form of electromagnetic waves.

3. Amplitude, A, maximum height of a peak Wavelength, λ, distance between peaks Frequency, f, number of peaks that pass a given point per unit time Period, T, time required for one cycle. Period = 1 / frequency
By multiplying the period of a wave with the speed of light, we can determine the wavelength λ=c*T

4. Electromagnetic Wave -- A wave emitted by vibrating electrical charges and composed of vibrating electric and magnetic fields
E.M. waves are classified by frequency or wavelength. Spectrum includes radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.
All of the forms of electromagnetic radiation can travel through empty space at the speed of light.
c = 2.998x108 m/s.

5. Light from the Sun looks as though it is white, but actually it consists of 7 colors.
ROYGBIV = Red, Orange, Yellow, Green, Blue, Indigo, Violet
The splitting of white light into its color components is called Dispersion.

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7. Colors depend on the frequency of light.
Low frequency – red light.
High frequency – blue light.
All colors blended together –white light.

8. Visible Light

9. Only a very small range of wavelengths, 400 nm - 700 nm, are visible to humans.
Because these wavelengths are small we describe them in terms of nanometers
(10-9m = 1 nm).

10. Particles in our atmosphere that are about the same size as the wavelengths of visible light cause the light from the Sun to scatter and split into individual colors.
Oxygen and Nitrogen, the main components of our atmosphere, scatter violet and blue light due to their small size (wavelength). This is why the sky appears to be blue in the daytime.

11. At sunrise and sunset the distance that the light has to travel from the Sun to our eyes is at its greatest. It’s going through a much thicker section of the atmosphere.
Most of the shorter-wavelength blue and violet light has already been scattered by the atmosphere, so the light that is seen by our eyes is mainly the long-wavelength red

12. The transparency of a material depends on the wavelength of light
The transparency of a material depends on the wavelength of light. Earth’s atmosphere is relatively transparent to visible light and radio waves, which are referred to as “windows” through which we can view space from a ground-based telescope.

14. Sometimes light acts like a particle and sometimes it acts like a wave.
It all depends on what sort of experiment you're conducting.
This is known as wave/particle duality.

15. Light consists of little particles, called photons (or quanta), each with an energy that is found by:
Photon energy =(Planck’s constant*c) / wavelength .
Einstein said that the frequency of light should make a difference in the Photoelectric Effect.