The different colors of light we perceive are a result of the varying frequencies (and wavelengths) of the electromagnetic radiation. Infrared radiation has lower frequencies than does visible light, and ultraviolet radiation has higher frequencies than visible light does. The primary colors are red (R), yellow (Y), and blue (B). Order these colors by their wavelength, shortest to longest. a) \(\mathrm{B}, \mathrm{Y}, \mathrm{R}\) b) \(B, R, Y\) c) \(\mathrm{R}, \mathrm{Y}, \mathrm{B}\) d) \(R, B, Y\)

Visible light wavelengths are the portion of the electromagnetic spectrum that can be detected by the human eye. Our perception of color comes from this narrow band of frequencies. In the visible spectrum, which ranges from about 380 nanometers to 750 nanometers, each color has a distinct wavelength.

For example, violet has the shortest wavelength, around 380 nm, and red has the longest wavelength, around 750 nm. The order of colors by increasing wavelength is commonly remembered by the mnemonic ROYGBIV — Red, Orange, Yellow, Green, Blue, Indigo, Violet. Within this sequence, each color smoothly transitions into the next, creating what we know as the 'rainbow' of visible light.

Understanding the order of light wavelengths is crucial not only for scientific study but also for practical applications such as color printing and display technology, where accurate color representation is essential.

Color perception in physics is rooted in the way our eyes detect light and how different wavelengths correspond to our experience of color. Inside our eyes, we have two types of photoreceptor cells: rods and cones.

Rods are responsible for vision at low light levels, while cones are active at higher light levels and enable us to see color. Humans typically have three types of cones, each sensitive to different wavelengths of light: one for long wavelengths (red), one for medium (green), and one for short wavelengths (blue).

Color Mixing

When light of different wavelengths stimulates these cones to varying degrees, we perceive a mixture of colors. For instance, yellow light stimulates both the red and green cones, which our brain interprets as the color yellow. This is also how televisions and monitors use red, green, and blue (RGB) pixels to create the range of colors we see on screens.

The frequency-wavelength relationship is a cornerstone of understanding electromagnetic waves. This relationship is expressed by the equation \( c = \lambda \times f \) where \( c \) is the speed of light (\( approximately 3 \times 10^8 \) meters per second), \( \lambda \) is the wavelength, and \( f \) is the frequency.

Since the speed of light is constant in a vacuum, an increase in frequency means a decrease in wavelength, and vice versa. This inverse relationship means that electromagnetic waves with higher frequencies (like ultraviolet light) have shorter wavelengths, while those with lower frequencies (like infrared) have longer wavelengths.

Thus, knowing the frequency of a wave allows us to calculate its wavelength and vice versa, a principle crucial for many technologies, from radio broadcasting to medical imaging.