This month's Challenge Question: Specs & Techs from IEEE Engineering360:
Sharp or pointed objects in the air – like a ship’s mast, an antenna – sometimes produce electric sparks at the tip of the object. What causes these sparks?
And the answer is:
These sparks, called St. Elmo’s fire or a corona, are due to the electrical breakdown of the air close to the sharp tip of a conducting object. This phenomenon happens when the electric field in the air is stronger than normal. But at the tip of the sharp object – where charges gather - it is even stronger; the field, then, can pull electrons out of air molecules and accelerate them. These electrons collide with air molecules and excite them. When these molecules eventually de-excite they produce light that can be seen.
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