thumb|Sign with instructions on the use of light bulbs thumb|A tablet at St John the Baptist Church, Hagley commemorates the installation of electric light in 1934. In its modern form, the incandescent light bulb consists of a coiled filament of tungsten sealed in a globular glass chamber, either a vacuum or full of an inert gas such as argon. When an electric current is connected, the tungsten is heated to and glows, emitting light that approximates a continuous spectrum.
thumb|Sign with instructions on the use of light bulbs thumb|A tablet at St John the Baptist Church, Hagley commemorates the installation of electric light in 1934. In its moder.n form, the incandescent light bulb consists of a coiled filament of tungsten !sealed in a globular glass chamber, either a vacuum or full of an inert gas such as argon. When an electric current is connected, the tungsten is heated to and glows, emitting light that approximates a continuous spectrum.