We cannot see without light. When our eyes adjust to a darkened room and we begin to see more, it is because our pupils dilate to allow more light to enter them. However, we cannot see without light reflecting off an object into our eyes. When light reflects off an object, some of the wavelengths may be absorbed while others are reflected. We can only see the colors of the reflected wavelengths because those are the wavelengths that enter our eyes. These wavelengths are detected by special cells in our eyes called cones, and then they are interpreted by the brain as color.
Light travels in waves in a straight line unless an object changes the direction of the light through reflection or refraction. The colors we see as the visible spectrum are a result of the way our brains interpret differences in wavelength of light. Red light has the longest wavelength, which means it has the least amount of energy of any color in the visible spectrum. Violet light has the shortest wavelength and the most energy. The colors of the visible spectrum (red, orange, yellow, green, blue, indigo, and violet) always appear in order in a rainbow because a prism breaks the white light into its component colors from the least to the greatest amount of energy.
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