Which visible color has the longest wavelength?

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A horizontal gradient bar displays the visible light spectrum from violet to red, labeled with corresponding frequency in terahertz, wavelength in nanometers, and photon energy in electron volts. — light When white light is spread apart by a prism or a diffraction grating, the colours of the visible spectrum appear. The colours vary according to their wavelengths. Violet has the highest frequencies and shortest wavelengths, and red has the lowest frequencies and the longest wavelengths.

Within the visible spectrum, the color with the longest wavelength is red.1

As part of the electromagnetic spectrum, visible light ranges from approximately 400 nm at the violet end to 700 nm at the red end. Because the energy of a photon is inversely proportional to its wavelength, the longer wavelengths associated with red light correspond to lower frequencies and lower energy levels compared to the shorter wavelengths found at the violet end of the spectrum.1