Technical light bulb. View of a lit technical electric light bulb. Bulbs produce light from filaments (centre), fine coiled tungsten wires which heat up and glow when an electric current is passed through them. Tungsten is an ideal material for filaments as it is strong and has a high melting point (3410 degrees Celsius). The interior of the bulb contains an inert gas, usually a mixture of nitrogen and argon. Air cannot be used as the oxygen it contains would corrode the tungsten. Whilst in use, the tungsten filaments gradually evaporate away until eventually they break. The numerous filaments contained in technical light bulbs make them very bright.