Which type of light has the longest wavelength?

Red light has the longest wavelength among the visible light spectrum. The visible light spectrum ranges from approximately 400 nanometers (violet) to 700 nanometers (red). Each color corresponds to a specific range of wavelengths, with red light sitting at the upper end of this range.

As the wavelength increases, the color shifts from violet through blue and green towards red, which is associated with longer wavelengths. This is why red light is often used in various applications, such as in signaling and photography, since it offers the ability to see in low-light conditions without affecting night vision significantly.

In contrast, green light has a shorter wavelength than red light, and blue and violet light have even shorter wavelengths. Thus, among the options provided, red light is indeed the color with the longest wavelength.