Light and colour

The different colours of light are electromagnetic waves with different frequencies and wavelengths. A triangular prism can produce a colour spectrum from white light, showing it is a mixture of all visible wavelengths. From red to violet in the spectrum, frequency increases and wavelength decreases. Higher frequencies refract further. Opaque objects transmit no incident light. Their colour depends on which wavelengths of incident light are reflected. Colour filters only transmit some wavelengths. The filter colour depends on the transmitted wavelengths.