Electric Field, Water Make Power Lines Hum

I DIDN’T KNOW THAT

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Question: Why do high-voltage electric power lines hum?

Answer: The hum is caused by the interaction of the alternating-current electric field carried by the wires and water on their surface, although researchers are not sure of the precise mechanism. It could be vibrations of the water surface, spitting from the tips of water droplets, or rapid expansion of air at the tips of the droplets caused by heating. Older power lines produce less noise than newer ones, probably because water is less likely to form into droplets on their surface. The intensity of the noise increases in a heavy rainstorm.