When we get a minor static electric shock, we often hear a noise associated with the shock.

Or for example, when you swat a fly with a zapper, you can hear a noise from the electric transfer.

What causes this noise?

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    $\begingroup$ The same thing that causes thunder, but on a smaller scale. see; en.wikipedia.org/wiki/Thunder $\endgroup$ – Adrian Howard Oct 12 '20 at 21:32
  • $\begingroup$ I guess these are two things: the outside noise that everyone else can here, and the "virtual" noise induced in some nerves that only you can "hear". I remember a a child licking my tong against an battery and "seeing" some light. $\endgroup$ – Gyro Gearloose Oct 12 '20 at 21:37
  • $\begingroup$ That noise is the sound of you screaming! $\endgroup$ – David White Oct 12 '20 at 23:17
  • $\begingroup$ @GyroGearloose, perhaps you have a touch of synesthesia. Not everybody who licks a 9V battery sees light. (Don't ask me how I know!) $\endgroup$ – Solomon Slow Oct 13 '20 at 1:20

The transfer of charge ionizes the air around it, making that zap sound.

  • $\begingroup$ But if you are touching the object, then the charge flows directly through you, no? How does it ionise the air if it doesn’t pass through the air? $\endgroup$ – PhysicsMathsLove Oct 13 '20 at 5:15
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    $\begingroup$ @PhysicsMathsLove around the moment you (dis)connect the source of charge to(from) the object to which the charge would flow, there's a tiny distance between them. The electric field strength, which is inversely proportional to distance, grows very high, which does break down the air gap. Then the instability of the contact makes this breakdown happen many times in small time period, leading to the buzz. $\endgroup$ – Ruslan Oct 13 '20 at 9:02

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