which color has the longest wavelength?

The color with the longest wavelength is red.

Wavelength is a measure of the distance between two adjacent peaks or troughs of a wave. It is a fundamental property of waves, including electromagnetic waves, such as light waves. The wavelength of a light wave determines its color, and the colors of the visible spectrum are typically arranged in order of increasing wavelength, from shortest to longest.

The colors of the visible spectrum, from shortest to longest wavelength, are: violet, indigo, blue, green, yellow, orange, and red. Red has the longest wavelength of these colors and is located at the opposite end of the spectrum from violet, which has the shortest wavelength.

The wavelengths of visible light are typically measured in nanometers (nm), which are one billionth of a meter. The wavelengths of red light are typically in the range of 620 to 750 nm, while the wavelengths of violet light are typically in the range of 380 to 450 nm.

The perception of color is a complex process that is influenced by a variety of factors, including the composition and structure of the materials that are being observed, the lighting conditions, and the characteristics of the observer's visual system. The colors that we see are the result of light waves being absorbed, reflected, or transmitted by the materials around us.