1. Chapter 22
The Nature of LiGHT

2. What is Light? Section 1
Light, just like sound, travels in waves. Sound travels as a longitudinal wave, light travels as a transverse wave.

3. Light: An Electromagnetic Wave
Light is a type of energy. It is also known as electromagnetic energy.
An electromagnetic wave is a wave that can travel through empty space or through matter.
An electromagnetic wave has a magnetic field and an electric field that travel at right angles to one another.
In an electromagnetic wave the electric and magnetic field are also at right angle, or perpendicular to the direction the wave is moving.

4. Light: An Electromagnetic Wave
The electromagnetic wave is produced by the vibration of a photon. A photon is an electrically charged particle.
Every electrically charged particle has an electric field around it. When the particle vibrates, it causes the electric field to vibrate.
If you have a moving electric field, you also create a magnetic field.
The vibration of the electric and magnetic field produces the electromagnetic wave.
The transfer of energy by electromagnetic waves is radiation.

5. The Speed of Light Nothing travels faster than the speed of light.
In a medium-free environment, light travels at 300,000 km/sec (or 9.5 trillion km/year).
In an environment with a medium, the light is slowed by the medium.
The light waves from the sun are the major energy sources on Earth.

6. Interactions of Light Waves Section 3
Electromagnetic waves interact in various ways that affect the way we view our universe.

7. Reflections
The law of reflection says that the angle at which light strikes a barrier will be equal to the angle at which it reflects off the barrier.
If an object produces its own light, it is luminous. If it reflects the light of another object it is said to be illuminated.

8. Absorption and Scattering
As light travels away from the object that produced it, the light gets dimmer and dimmer. This is due to absorption and scattering.
When energy is transferred from a light wave to particles of matter that is absorption. This causes the light to become dimmer.
Scattering is an interaction between light and matter that causes the light to change direction.
After colliding with matter, light scatters in all directions. Light with a shorter wavelength is scattered more than that with a longer wavelength. This is why the sky appears blue.
Scattering is why the sky is blue! NOT it reflects the color of the ocean, if that were true why isn’t the sky green over pastures or the rain forrest.

9. Refraction
Refraction is the bending of light as it passes from one medium to another.
Refraction occurs because the speed of light varies according to the medium it is traveling through.
The part of the wave that first enters the new medium starts traveling at a different speed before the rest of the wave does. This causes the bending to occur.
Refraction results in optical illusions.
Refraction also results in the formation of rainbows as the sunlight is refracted by the water drops in the atmosphere.
Each color of light has a different wavelength. The colors with the shortest wavelength bend more than the ones with longer wavelength.

10. DIFFRACTION
Diffraction is the bending of waves around barriers or through openings.
The amount a wave diffracts is determined by its wavelength and the size of the barrier/opening.
Light waves cannot diffract very well around large objects.

11. Interference Interference occurs when 2 or more waves overlap.
Interference may be destructive, which results in less amplitude than the original wave, or it may be constructive, which results in greater amplitude than the original wave.