Visible light has a range of wavelengths with violet the shortest wavelength and red the longest. Sunlight or simply light is made up o all the wavelengths of electromagnetic radiation that our eyes can detect. It is thereore visible to us and other wavelengths are invisible. There is a spectrum of electromagnetic radiation from very short to very long wavelengths. Shorter wavelengths such as X-rays and ultraviolet radiation have high energy; longer wavelengths such as infrared radiation and radio waves have lower energy. Visible light has wavelengths longer than ultraviolet and shorter than infrared. The range of wavelengths of visible light is 400 to 700 nanometres. When droplets of water in the sky split sunlight up and a rainbow is formed, different colours of light are visible. This is because sunlight is a mixture of different wavelengths, which we see as different colours, including violet, blue, green and red. Violet and blue are the shorter wavelengths and red is the longest wavelength. The wavelengths of light that are detected by the eye are also those used by plants in photosynthesis. A reason for this is that they are emitted by the sun and penetrate the Earth€s atmosphere in larger quantities than other wavelengths, so are particularly abundant.