Physics Resources - What is Light?

Most of the light that is present on Earth originates from the sun, and a large percentage of it comes from fire, electrical devices, and other sources. Light is composed of billions of particles called photons. When these photons move at certain wavelengths, light becomes visible to the human eye.

• Light Information: This article provides some interesting information on light.

• Light Facts: Excellent compilation of facts about light.

• What is Light?: A webpage that gives a clear definition of light.

• Understanding Light: Comprehensive discussion on the basic characteristics of light.

• The Science of Light: Discovering light from a scientific perspective.

• Properties of Light: A model that exhibits the properties of light.

• Light Videos: Collection of educational videos about light.

Light Waves

Light is a form of electromagnetic wave. It can travel through vacuum, and it does not have to depend on the presence of matter to get from one place to another. It can move from the sun to the Earth and across indoor spaces. Human beings are surrounded by electromagnetic waves everywhere they go. Light travels at different wavelengths. When its wavelengths are longer, it becomes visible light. Light with short wavelengths is called ultraviolet light.

• Light Waves: A fun and easy way to understand light waves.

• Light and Electromagnetic Waves: This presentation provides an insight into light as an electromagnetic wave.

• Visible Light Waves: An excellent explanation of visible light waves.

• Is Light a Wave?: Discussions on whether light is a wave or a particle. 

Colors

The color of visible light is determined by its wavelengths. The color with the longest wavelength is red, and the color with the shortest wavelength is violet. When white light travels through a prism, it will be broken up into seven different colors, which are red, orange, yellow, green, blue, indigo, and violet. The water vapor in the Earth’s atmosphere acts as a prism and brings colors to the whole world.

• The Colors of Light: A good tutorial on the colors of light.

• Light and Color: Explanation of the relationship between light and colors.

• Color and Wavelengths: Document with a diagram that shows the wavelengths of different colors.

• Formation of Rainbows: Find out how rainbows are formed by reading this document.

• What is Color?: An overview of the colors of light.

Reflection

Reflection happens when a ray of light hits and bounces off a surface. The angle of the reflection is equal to the angle at which the light approaches the surface. If the surface is flat, smooth, and well-polished, all light rays will be reflected in the same direction. A good example of the reflection of light is the mirror.

• Understanding Reflection: An interactive presentation that explains the concept of reflection.

• Absorption and Reflection of Light: Learn how light is absorbed and reflected by watching this video.

• Reflection and Surfaces: Images showing the reflection of light on different types of surfaces.

• Reflection and Refraction: An illustrated document that explains the reflection and refraction of light.

Refraction

Refraction refers to the bending that occurs when light travels through two materials of different densities. Density of matter affects the speed of light, and this is the reason for the refraction of light. The degree of refraction is determined by the difference between the densities of the two media. Refraction can be seen when a straw is inserted in a glass of water. 

• What is Refraction?: A concise definition of refraction.

• Understanding Refraction: Brief explanation of the refraction of light.

• Observing Refraction: Observe the refraction of light in this great educational video.

• Lesson on Refraction: Animation demonstrating the process of refraction.

Light Experiments and Science Fair Projects

One of the best ways to learn about light is to conduct light experiments and science fair projects. Experiments and projects can be easy or difficult, and they can show students the way that light behaves under different circumstances. Below is a list of websites with interesting light experiments or science fair projects.

• Light Wave Experiment: An experiment that proves that light is a wave.

• Reflection Activities: These activities teach students about the reflection of light.

• Refraction Experiments: Perform these experiments to learn about the refraction of light.

• Light Science Projects: Some great ideas for light science projects.

• Light Experiments: A wonderful selection of experiments that provide a better understanding of the properties and characteristics of light.

• More Light Experiments: Another list of interesting light experiments.