I was just trying something with a mosquito zapper (the racket type) and experienced something.

You see, there are three "nets" in a mosquito zapper. When any one of the outer nets comes in contact with the net in the middle, a spark is seen.

I took my compass (the one used for drawing circles) and a metallic pen and attached the compass to the net in the middle and the metallic pen to one of the outer nets. I was bare feet and they were touching the ground. I had pressed the racket's on button before doing this. As soon as I touched the pen and the compass, I expected to see a spark between them but something else happened. I felt like someone punched me pretty hard with both of his fists in the back. I screamed as a response. I was shaking after this.

Did the current flow through my body first as I was in direct contact with the earth? How dangerous could it have been?

  • $\begingroup$ Did you remove anything from the zapper in order to do your experiment? $\endgroup$
    – Bob D
    Apr 29, 2020 at 11:31
  • $\begingroup$ @BobD Not a thing, it was in the same condition as it was in when bought. $\endgroup$ Apr 29, 2020 at 11:32
  • 1
    $\begingroup$ Electrical devices are not toys to experiment with. I strongly advise everyone to be extremely cautious with them. Even mundane looking devices can have e.g. capacitors capable of killing if discharged accidentally. This has happened with e.g. battery operated camera flashes - it doesn't have to be a mains device and the device does not even have to be on. $\endgroup$ Apr 29, 2020 at 12:28
  • $\begingroup$ An interesting question is why it felt like someone punched you pretty hard with both of his fists in the back. I would guess a spark occurred there, so the current would then have exited at your back instead of your feet. So the question is, were you sitting on a chair, did the back rest have a metal edge, and was there bare skin exposed near that metal? (Obviously no simultaneous spark would occur from the zapper to your hand, due to the intermediary compass) $\endgroup$
    – jkien
    Apr 29, 2020 at 15:29
  • $\begingroup$ @jkien I just realized something. The compass and the metallic pen did not meet. If they would have met, then the electric discharge would have occurred between them (I have tried this using wires and I was properly insulated back then). Instead, I became the mosquito (kind of). I think that the charge didn't even flow to the ground and my feet might have been on a mat beneath (I'm not sure about that). Maybe (and most probably), the charge did flow through my body and discharged while doing so (if that's possible). $\endgroup$ Apr 30, 2020 at 11:00

2 Answers 2


I am by no means an expert in physics, but from what you described it seems clear that the current flowed through the compass, through you and then to earth.

The spark only occurs when the 'easiest' way for the circuit to complete is by jumping from one net to the other (like when a mosquito bridges the gap). One net is at a high potential, the other is at a low potential. Similar to how water at the top of a waterfall flows, when you bridge the gap current flows.

In this case, you bridged the gap with your compass, but you were touching the compass, and you were earthed to the ground. So instead of the charge in the high potential net flowing to the low potential net, the charge flowed through you to the earth, which is at zero potential - even less. You can think of this as digging a hole at the bottom of the waterfall. It now has farther to fall, so it's not going to stop where it stopped before.

I wouldn't recommend doing this again - but you should have made sure you were well insulated from the compass. If there's a plastic handle, hold that, or wear thick insulating gloves. Also - definitely wear shoes. If you've ever tried touching an electric fence in bare feet, you'll know that having no insulation from the earth makes this much worse.

I have tried to keep this answer as non-technical as possible - partly so that it's understandable (I don't know what level of physics you have) and partly because I am no expert myself.

As for how dangerous it could have been - it seems that you have reached the peak danger from a mosquito net. Please, please please don't mess with electricity like this - especially not mains electricity. A mosquito net might be uncomfortable, but if you did the same with a mains socket you could very easily be killed. Electricity is no joke.

  • $\begingroup$ That was a nice explanation and making the answer as non-technical as possible was a great thing to do. I know the basics of electricity by the way (I'm in $10^{th}$ grade). I was just wondering that this shock didn't feel like a vibration at all, it just fell like, well, a hard punch!!! That was probably because my muscles contracted forcefully and harder than usual. I was just so surprised that a mosquito zaper could do that much... $\endgroup$ Apr 29, 2020 at 11:56

As I understand it, insect "zappers" tested and certified for safety involve thousands of volts but very low available current such that they should not involve a risk of lethal electric shock. It is basically an electrostatic discharge device.

When an insect is in the air between the "electrodes" (however they may be designed) of the device, they reduce the impedance of the gap electrodes resulting in a discharge of current and destruction of the insect (the "zapping" sound one hears coming from the device during operation).

The current you experienced may not have been due to your contact with the earth. It would necessitate the high voltage be referenced to earth. If the voltage originated from the output of a step up isolating (from ground) transformer, current to the earth may not have been involved. It's more likely you experienced the consequences of putting yourself directly across the output. But it really depends on the design of the zapper. All of this assumes that there was not some defect associated with the device.

In any event, even though the normal intended current output of these devices is unlikely to be potentially lethal, you will certainly feel it and it won't be pleasant. I'd advise you not to experiment further with this, or any other electrical devices.

Hope this helps.


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