The Science of Light

What is Light?

• Light is a form of electromagnetic energy vital for sight.
• Sunlight is a primary source of light.
• Light travels in a straight line.
• Visible light is only a portion of the electromagnetic spectrum.

Types of Light

• Humans can only see a small range within the light spectrum called visible light.
• There are other types of light, including ultraviolet and infrared, humans cannot see.
• Insects have the ability to see infrared light.

Speed of Light

• Light travels extremely fast (almost 300,000 kilometers per second or 186,000 miles per second).
• It takes approximately 8 minutes for sunlight to reach Earth.
• Light from distant stars may have already ceased to exist before it reaches the Earth.

Colors of Light

• Visible light is made up of various wavelengths that correspond to different colours.
• Three primary colors are red, green and blue.
• Mixing these colors generates secondary colors: yellow, cyan, and magenta.
• White light is created when all colors combine.

Why the Sky is Blue

• The atmosphere is composed of tiny particles called molecules.
• Sunlight's shorter wavelengths (blue light) are scattered more effectively by these molecules than longer wavelengths (like red).
• This scattering phenomenon is why we see a blue sky.

Why the Sunset is Red/Orange

• As the sun sets, the light has to travel through more of the atmosphere.
• The blue light is scattered away.
• The longer wavelengths (red and orange) are more prominent, causing a reddish or orange sunset.