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The electrostatic world of insects

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Re: The electrostatic world of insects

#3

Post by chmod775 »

amelius wrote: post #2

If insects can build up 5 kilovolts while flying, then why can I zap flies with a fly-zapping tool that presumably runs at a similar or lower voltage?

When they fly, there's no current. They just have potential compared to ground. Also presumably their electrical charge is very low and there's going to be hardly any amps when they discharge.

In the same vein, if your carpet gives you a static shock, that's likely going to be thousands of volts. But obviously there isn't actually a lot of energy stored (all you did was convert some friction), so there's next to no amperes, little work the electricity can do, and thus no harm.

Re: The electrostatic world of insects

#4

Post by codeflo »

amelius wrote: post #2

If insects can build up 5 kilovolts while flying, then why can I zap flies with a fly-zapping tool that presumably runs at a similar or lower voltage?

It's not a bad question, these units of measurements are always a bit confusing. You can similarly ask why for humans, rubbing a balloon is harmless, although that builds up 30 kV of static electricity, while touching a 230 V power socket can kill you.

Voltage is merely the "pressure" that charged particles experience. Voltage alone tells you nothing about how much charge is actually available once electricity is allowed to flow. And that's where the harm comes from. For static electricity, when you touch something, you get maybe a microcoulomb, once, and it's gone. For a power socket, you get up to 16 coulombs per second continuously.

Re: The electrostatic world of insects

#7

Post by brk »

amelius wrote: post #2

If insects can build up 5 kilovolts while flying, then why can I zap flies with a fly-zapping tool that presumably runs at a similar or lower voltage?

For many of the same reasons that birds can land on high voltage lines without risk of being electrocuted. A flying insect has stored voltage with no path to ground, or any point with low resistance and lower potential.

When you hit a flying insect with a zapper you are supplying a high potential and low potential electrode. The insects body completes the circuit and the stored voltage is routed through the insect, rendering it a flightless blob of goo.

Re: The electrostatic world of insects

#9

Post by ocfnash »

codeflo wrote: post #4
amelius wrote: post #2

If insects can build up 5 kilovolts while flying, then why can I zap flies with a fly-zapping tool that presumably runs at a similar or lower voltage?

It's not a bad question, these units of measurements are always a bit confusing. You can similarly ask why for humans, rubbing a balloon is harmless, although that builds up 30 kV of static electricity, while touching a 230 V power socket can kill you. Voltage is merely the "pressure" that charged particles experience. Voltage alone tells you nothing about how much charge is actually available once electricity is all…

As a kid, the alliterative mnemonic we were taught was "current kills".

Re: The electrostatic world of insects

#10

Post by dmd »

ocfnash wrote: post #9
codeflo wrote: post #4

Earlier quoted context omitted.

It's not a bad question, these units of measurements are always a bit confusing. You can similarly ask why for humans, rubbing a balloon is harmless, although that builds up 30 kV of static electricity, while touching a 230 V power socket can kill you. Voltage is merely the "pressure" that charged particles experience. Voltage alone tells you nothing about how much charge is actually available once electricity is all…

As a kid, the alliterative mnemonic we were taught was "current kills".

"It's the volts that jolt but the mils [milliamps] that kills."
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