# Unit 9 Lesson 1: Light Waves

We’re going to take a deep look at the nature of light and its behavior during different types of experiments to try to figure out its properties. Light can travel through the vacuum of space as well as solid substances like glass. Energy exists as either matter or electromagnetic radiation.

Scientist are still trying to make heads or tails of this thing called light, and near as they can tell, it sometimes interacts like a particle (like a marble) and other like a wave (like on the ocean), and you really can’t separate the two because they actually complement each other.

Light can be either a wave or a particle, but not both at the same time. Which one it is will depend on what it’s doing. In this section, you’ll be able to figure out how intensity (how bright), frequency (wavelength), polarization (the direction of the electric field), and phase (time shift) all affect the kind of light you see and don’t see. Most light isn’t detectable by the human eye, which makes studying light more like investigating a crime scene. You’ll quickly be puzzling the pieces together to explain why pencils in a glass of water appear broken, why light beams can fry an egg, and how to build a telescope.

## Scientific Concepts:

• Light can travel through a vacuum, like space.
• Light can change speeds, but the maximum speed is through a vacuum (186,282 miles per second).
• Low frequency electromagnetic waves are called radio waves, which are not the same as sound waves.
• Light you can see (visible light like a rainbow) makes up only a tiny bit of the entire electromagnetic spectrum.
• Light has wavelength (frequency, or color), intensity (brightness), polarization (direction), and phase (time shift).
• Prisms unmix light into its colors (wavelengths).
• Light changes speeds when it passes through a different material (like water, glass, or fog).
• Lenses work to bend light in a certain direction (refraction).
• Concave lenses work to make objects smaller (door peep hole), convex lenses make them larger (magnifying lenses).