How they make bulbs from a ribbon of glass?

Making light bulbs is an intricate and highly automated factory process in which the bulbs are blown into shape in moulds from a continuous ribbon of molten glass.

A vital component of the bulbs is the filament, a coil of tungsten wire one hundredth of a millimetre thick. This is the part that becomes white hot and produces the light when electricity flows through. It is mounted on a glass time stem and clamped to the end of thicker wires that pass through the stem of the base of the bulb.

When the stem is inserted in the bulb, any oxygen in the bulb is eliminated (otherwise it would cause the coil to oxidise, greatly reducing its life). The bulb is then filled with an argon/nitrogen mixture. It is sealed and a metal is cemented in place.

A modern bulb-making machine can produce 30 bulbs in a few minutes, each able to pour out light for at least 1000 hours. Gradually, however, the metal filament evaporates. Eventually it will break and the light will fail.

Whistling bulbs

Why do some bulbs whistle before they fail? In fact, the filament breaks while the bulb is alight, but it stays alight because electricity arcs over the gap. It is the arc that emits the high-pitched whistle.


Picture Credit : Google