When electricity is pushed with enough voltage to produce a spark, it changes the air from a gas into a state of matter called plasma. Plasmas conduct electricity and often give off light. A good example is a neon sign. When colorless neon gas is changed to plasma, it glows a reddish orange. If the gas inside is argon instead of neon, it glows blue. The air around us is mostly nitrogen, which gives off violet and ultraviolet light as a plasma.