Light is a form of energy that travels in waves. The different colors we see are our eyes’ interpretation of these waves traveling at various lengths. When natural white light passes through a medium, such as water droplets in a rainbow, it separates into its constituent colors. Each distinct hue in the spectrum corresponds to a specific physical measurement of that light wave.
The Color with the Shortest Wavelength
The color with the shortest wavelength within the visible spectrum is violet light. This light occupies the narrowest band at the very end of the colors detectable by the human eye. The approximate wavelength range for violet light is between 380 and 450 nanometers.
Because the wavelength is short, violet light also carries a higher amount of energy compared to the other visible colors. This characteristic places violet light immediately adjacent to ultraviolet radiation on the full energy spectrum.
Defining Wavelength and the Electromagnetic Spectrum
A light wave’s wavelength is the physical distance between two successive peaks or troughs of the wave as it travels through space. This measurement is represented in units of distance, such as nanometers. The wavelength directly determines the wave’s frequency, which is the number of wave cycles that pass a fixed point in one second.
Wavelength and frequency have an inverse relationship; a shorter wavelength corresponds to a higher frequency. Therefore, the short waves of violet light oscillate more rapidly than the waves of other visible colors. The entire range of light, including visible light, radio waves, and X-rays, is organized into the electromagnetic spectrum.
Visible light is only a minute segment of this vast electromagnetic spectrum, which spans from long radio waves to short gamma rays. The visible portion is bounded by longer-wavelength infrared radiation and shorter-wavelength ultraviolet radiation. All light travels at the same speed in a vacuum, with the difference in color being solely a function of its physical wave properties.
Mapping the Visible Light Order
The colors of the visible spectrum follow a fixed order, moving from the longest wavelengths to the shortest. This progression starts with red light, continues through orange, yellow, and green, then transitions into blue, indigo, and finally, violet. The light wave progressively shortens as one moves through this sequence.
Red light sits at the opposite end of the spectrum from violet, with wavelengths measuring between 620 and 750 nanometers. As the color transitions from red toward orange and yellow, the light waves become incrementally shorter. Green light represents the middle of the visible spectrum, possessing a moderate wavelength and frequency.
Moving from blue to indigo and then to violet, the light waves continue to compress. This progression of color by wave size is often remembered using the mnemonic ROYGBIV. The mnemonic stands for Red, Orange, Yellow, Green, Blue, Indigo, and Violet.