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In: Technology
The big, high power lights used for things like football stadium lighting or lighting very big spaces like a parking lot?
They’re a form of arc-lamp. There are two connections inside the glass bulb, but not with a wire between them.
At switch-on, a very high voltage (tens of kilovolts) is generated by the light fitting, and sparks across the gap between the two connections (the clunk and the buzz). Once this has happened for a second or two, the gas inside the glass will conduct electricity. The fitting then provides a lower voltage (but lots of current) and the spark (arc, to use the correct term) remains present. The gas mixture inside the bulb responds to the heat generated by the arc and glows very brightly indeed, thus providing the light from the fitting.
They’re used because they’re relatively energy-efficient, although modern large LED fittings are beginning to replace them.
https://en.wikipedia.org/wiki/Arc_lamp
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