When an element or compound is heated, it undergoes a process called emission, where it releases (emits) electromagnetic radiation across a range of wavelengths, including visible light, as a result of electron transitions or atomic/molecular vibrations.

  • The Sun is a prominent emission source, radiating the entire electromagnetic spectrum, encompassing visible light, radio waves, infrared, ultraviolet, X-rays, and gamma rays.
  • Elements and compounds emit electromagnetic radiation as a result of electron transitions or atomic/molecular vibrations.
  • The Sun emits electromagnetic radiation due to the intense heat generated by nuclear fusion processes within its core.
  • Artificial light sources, including lamps, LEDs, and fluorescent lights, emit specific ranges of wavelengths within the visible spectrum, which corresponds to different colours when perceived by humans.
  • When looking directly at a light source, its colour corresponds with the wavelengths being transmitted.
  • Electronic displays, such as computer screens and televisions, use emission to generate colours by emitting light at specific wavelengths corresponding to the primary colours of red, green, and blue.
  • When RGB primary colours are combined in varying proportions they can generate a wide gamut of approximately 16 million colours.
  • Digital printing does not rely on emission. Printing involves the reflection of light off a white surface such as a sheet of paper. The surface is overlaid with inks. Transparent inks allow light to pass through to the paper where it is reflected back towards the observer. The colour of the light determines which wavelengths pass through the ink after reflection and so which colours an observer sees.