Properties of Light

Understanding the nature of light, color, and the visible spectrum

Topics

How do we see color?

We see color through specialized cells in our eyes called cones that detect different wavelengths of light. There are three types of cones sensitive to red, green, and blue wavelengths. Our brain combines signals from these cones to create the perception of all colors.

What is color?

Color is how our eyes and brain perceive different wavelengths of light. Visible light wavelengths range from about 400 nm (violet) to 700 nm (red), with different wavelengths appearing as different colors. Color depends on both the light source and how objects reflect or transmit light.

What is the speed of light?

The speed of light in vacuum is approximately 299,792,458 meters per second (about 186,282 miles per second), often denoted as 'c'. It's the fastest speed possible in the universe and is constant for all observers, regardless of their motion.

What is the visible spectrum?

The visible spectrum is the range of electromagnetic wavelengths that human eyes can detect, approximately 400-700 nanometers. It includes all the colors we can see, from violet (shortest wavelength) through blue, green, yellow, orange, to red (longest wavelength).

Why is light both a wave and a particle?

Light exhibits wave-particle duality—it behaves as both waves and particles depending on how we observe it. Wave behavior appears in interference and diffraction, while particle behavior (photons) appears in interactions with matter. This duality is fundamental to quantum mechanics.