Animated Solution for Physics - Electromagnetic Waves: Red light differs from blue light as they have

Wavelengths and Frequencies

Have you ever wondered what makes red light look red and blue light look blue? It all comes down to the fundamental properties of electromagnetic waves. Light is a wave, and like all waves, it has a speed, a wavelength, and a frequency.

In a vacuum, all electromagnetic waves, regardless of their color, travel at the exact same speed: the speed of light, denoted by $c$ ($3\times 10^8\text{ m/s}$). The relationship between these three properties is beautifully captured by a single, elegant equation:

Here, $\lambda$ represents the wavelength (the distance between two consecutive peaks of the wave), and $ u$ represents the frequency (how many peaks pass a given point in one second).

When we look at a rainbow or the visible spectrum (often remembered by the acronym VIBGYOR), we are seeing light of different wavelengths. Red light sits at one extreme end of this visible spectrum, while blue light sits near the other end.

By definition, red light has a longer wavelength than blue light:

Imagine the red light wave as a long, lazy ocean swell, while the blue light wave is like quick, choppy ripples.

Now, let's bring our master equation back into the picture. If we rearrange it to solve for frequency, we get:

Because the speed of light $c$ is a constant, this equation tells us that frequency and wavelength are inversely proportional. If the wavelength goes up, the frequency must go down to keep the product constant.

Since red light has a longer wavelength than blue light, it must inherently have a lower frequency:

Therefore, when we compare red light to blue light, we find that they are distinct in both of these fundamental properties. They have different wavelengths and different frequencies. This simple yet profound realization is the key to understanding not just color, but the entire electromagnetic spectrum!