Struck by lightning

[modest]

So... I was struck by lightning the other day. I was sitting at my computer (as usual :eek2:) during an electrical storm. The house was hit (I assume) at which time I felt as if someone behind me hit me in the side of the head with a baseball bat. When my senses returned I felt the side of my head and neck tingling and noticed the power was out in the house. I deduced that I'd been electrocuted. I'm happy to say, besides a somewhat serious burn on my left ear, I'm fine. But I thought this would make an interesting question to pose,

 

The distance between me and the lowest point of the ceiling fan above me at the time was just over a meter (1.1m - 1.2m). What was the minimum voltage I took? Any takers?

 

~modest

[freeztar]

So... I was struck by lightning the other day.

 

;)

 

I'm sorry. I know it's not funny, but the nonchalant opening statement gave me a chuckle.

 

So...I was stabbed the other day...ho-hum...

 

I'm glad you're alright mate! That would have freaked me out! Was anyone else there when it happened. You can't just get away with saying you were struck by lightening and then go straight into a scientific investigation. Details!

 

I was sitting at my computer (as usual :eek2:) during an electrical storm. The house was hit (I assume) at which time I felt as if someone behind me hit me in the side of the head with a baseball bat. When my senses returned I felt the side of my head and neck tingling and noticed the power was out in the house. I deduced that I'd been electrocuted. I'm happy to say, besides a somewhat serious burn on my left ear, I'm fine.

 

Have you tested your hearing in that ear? I assume you went to a doctor?

 

But I thought this would make an interesting question to pose,

 

The distance between me and the lowest point of the ceiling fan above me at the time was just over a meter (1.1m - 1.2m). What was the minimum voltage I took? Any takers?

Right, on to the science then.

 

I don't exactly know how to approach this problem as I'm not savvy with electricity. Though, I would assume we would need to know a lot more information like average bolt voltage, house voltage (maybe? I assume 120 per US standards), and of course, formulas.

 

I know the standard voltage formula, but I'm not sure how that changes over gaps. I assume we need some calculus, eh? (well, maybe not if we assume no arcs?)

 

I'll try and research this, but a starting place would be nice for us mere mortals. :(

[UncleAl]

Seek immediate medical attention for your ear burn. The internal collagen scaffolding can serve as a matrix for bacterial glycocalyx (biofilm) formation if infected. That sort of problem is generally removed rather than cured. If you have second degree burns the site must be kept safe until it heals to sealed over (about a month). Prescription Silvadene (generic silver sulfadiazine will not do) burn cream can be unpleasant but it is essential. Third degree burns call for skin autografts. Serious burns will not heal to a good conclusion without professional attention.

 

Electrical burns are notorious for minor surface damage but serious deep tissue necrosis along the conduction channel. Collagen softens and melts when heated under burns while remaining biologically viable, hence the disfigurement of facial burns. This definitely calls for a competent physician's care.

 

It's not the volts it's the amps.

[freeztar]

It's not the volts it's the amps.

 

Right, like tazers.

 

So, would it be best to only consider amps or should wattage be used?

[modest]

:(

 

I'm sorry. I know it's not funny, but the nonchalant opening statement gave me a chuckle.

 

So...I was stabbed the other day...ho-hum...:)

 

:) I had a similar chuckle after it happened. I believe the exact thought was "you've gotta be kidding me"

 

I'm glad you're alright mate! That would have freaked me out! Was anyone else there when it happened.

 

Thank you. I was alone.

 

You can't just get away with saying you were struck by lightening and then go straight into a scientific investigation. Details!

 

There's not much to tell :) If you've done any boxing, it felt like a good right hook. I was "rocked" for a sec.

 

I don't think I was grounded at the time. No damage to the house :)

 

Have you tested your hearing in that ear? I assume you went to a doctor?

 

Hearing's fine. I actually had an unrelated doctors appt. today so I told her about it. She had a look at my ear, had a good laugh, and recommended Neosporin.

 

 

 

 

 

 

Seek immediate medical attention for your ear burn.

 

Thank you for the concern and the good medical info.

 

It's not the volts it's the amps.

 

If we know the resistance which would be easy enough to find knowing the electrical resistivity of air along with the cross section clearly left on my ear and the size of the pull cord on the fan (we'll say 1cm²) then all I can think to use is V=IR. My OP was asking for voltage and you say it's amps (which is 'I' or current). Since resistance is the ratio of voltage and current, perhaps this question is unanswerable in either voltage or amps having only the info we have...

 

~modest

[pamela]

technically modest, if you were electrocuted, you would be dead~ electrical shock may be a better word.I feel your pain.Once i took on the entire voltage of a restaurant.It shook me for roughly 10 minutes, threw me 50 feet, and then i continued to shake profusely for another 10 or so, all the while attempting to say 99999911111111111111 to the hostess.Who just screamed and did nothing.

[freeztar]

This is from initial research, but it at least gives some tangible numbers and a fun new term (for me at least), Keraunopathy. (and Keraunomedicine)

 

Says Gourbière, "The pathology of lightning, or keraunopathy, is known only to a few specialists."

 

Most doctors are more familiar with electrical shocks, such as those received by industrial workers when they have an accidental run-in with high-voltage equipment. But lightning injuries are not the same as electrical shocks. For one thing, the contact voltage of a typical industrial electrical shock is 20 to 63 kilovolts, while a lightning strike delivers about 300 kilovolts.

When lightning strikes people

[lemit]

Let's see. First, I hope you saw a doctor. With a distinct burn on your ear, there might be a possibility of internal injuries.

 

Growing up on a farm in Missouri when rural electricity was finally getting to us, I played with electricity from electric trains to electric fences, homemade electric motors, and even some arc welding. We also got a lot of the natural stuff (with St. Elmo's fire, ball lightning, chain lightning, and some other forms I've not seen descriptions of). From my memories of those experiences, I'd say you took a pretty substantial hit.

 

Since my experiments with electricity were much less well documented than those of Franklin, I'd love to see some numbers, although I know they'd just be educated guesses.

 

--lemit

 

p.s. Guesses are just fine as long as we don't pretend they aren't guesses.

[Jay-qu]

Modest that sure makes one crazy story, I hope your burn heals up well!

 

No dice trying to use simple V=IR law here, that only works for Ohmic devices (linear resistive response) and most devices only approximate this anyway over a suitable region. But I guess you could try it as a first approximation. So we could try to estimate what your bodies resistance is, and then assuming that you are not posting from beyond the grave you must have taken <70mA.

[modest]

Modest that sure makes one crazy story, I hope your burn heals up well!

 

No dice trying to use simple V=IR law here, that only works for Ohmic devices (linear resistive response) and most devices only approximate this anyway over a suitable region. But I guess you could try it as a first approximation. So we could try to estimate what your bodies resistance is, and then assuming that you are not posting from beyond the grave you must have taken <70mA.

 

Thanks, Jay. I don't see how you're getting amps from V=IR without knowing V, or, perhaps you're estimating what the human body can take in the way of current before it gets seriously injured?

 

From the CRC Handbook of Chemistry and Physics it looks like the electrical resistivity of air is ~4x10¹³ ohm-m. If that's correct then for 70mA to jump 1.1 meters would be...

 

[math]R= \rho \frac{l}{A}[/math]

[math]R= 4 \times 10^{13} \ \Omega \frac{1.1 \ m}{0.0001 \ m^2}[/math]

[math]R= 4.4 \times 10^{17} \ \Omega[/math]

well, that seems a bit high...

 

[math]V= IR[/math]

[math]V= (0.07 \ amperes)(4.4 \times 10^{17} \ \Omega)[/math]

[math]V= 3 \times 10^{16} \ V[/math]

 

Yeah, a full on bolt of lightning only has about a billion volts, so that can't be right. I think perhaps you're right that V=IR would be a very bad approximation here. That, and resistivity probably isn't constant over voltage either (it would ionize)...

 

:shrug:

 

~modest

[Jay-qu]

Yeah what implied is that the max current that could have passed through you was 70mA otherwise you would likely be seriously injured or killed (sorry to be so blunt).

 

You are correct in saying that V=IR doesnt apply for lightning in air also. Normally when lightning strikes there is an initial pulse and then the large strike (look up ultra slow motion lightning on you tube), presumably this is because the first strike ionizes the air creating a 'path' for the large strike.

 

I think estimating the resistance of the human body would be a better approach here. We can use the resistivity of salt water (or blood if you can find it) as a first approximation as that is what most of our body is made of. Then it remains to choose a path length and cross section. Do you know where the lightning left your body? some people get more pronounced burns where the lightning exits their body

[modest]

Yeah what implied is that the max current that could have passed through you was 70mA otherwise you would likely be seriously injured or killed (sorry to be so blunt).

 

No need not to be blunt. That's probably the best limiting factor :)

 

You are correct in saying that V=IR doesnt apply for lightning in air also. Normally when lightning strikes there is an initial pulse and then the large strike (look up ultra slow motion lightning on you tube), presumably this is because the first strike ionizes the air creating a 'path' for the large strike.

 

Yes, that makes good sense

 

I think estimating the resistance of the human body would be a better approach here. We can use the resistivity of salt water (or blood if you can find it) as a first approximation as that is what most of our body is made of. Then it remains to choose a path length and cross section. Do you know where the lightning left your body? some people get more pronounced burns where the lightning exits their body

 

Very good. My foot was tingling after the incident. Although there's no burn there, I'm quite sure that was the exit point—I was barefooted on hardwood flooring. Although the burn on my ear is slightly larger than a cm^2, I think that would be a fine estimation (this is really all for fun anyway :))

 

So, voltage... the resistivity of blood is reportedly 140 ohm-cm from: Handbook of electrical hazards and ... - Google Books

 

In the way of voltage with 70 mA that should give:

 

[math]R= \rho \frac{l}{A}[/math]

[math]R= 1.4 \ \Omega \ m \frac{1.7 \ m}{0.0001 \ m^2}[/math]

[math]R= 23800 \ \Omega[/math]

 

[math]V= IR[/math]

[math]V= (0.07 \ amperes)(23,800 \ \Omega)[/math]

[math]V= 1666 \ V[/math]

 

Darn... That seems somehow unimpressive :( I was hoping to add "So... I got shocked with 50,000 volts the other day" to the story :hihi:

 

~modest

[modest]

technically modest, if you were electrocuted, you would be dead~ electrical shock may be a better word.I feel your pain.Once i took on the entire voltage of a restaurant.It shook me for roughly 10 minutes, threw me 50 feet, and then i continued to shake profusely for another 10 or so, all the while attempting to say 99999911111111111111 to the hostess.Who just screamed and did nothing.

 

Ouch. We need to start a club—a paranoid group of people who think electricity is out to get them :hihi: We could hand out flyers and scare the locals. Good times :cheer:

 

~modest

[Jay-qu]

Your bodies potential difference was ~1666V, the lightning would have had a larger voltage but most of the potential difference was 'spent' in the atmosphere.

[freeztar]

Your bodies potential difference was ~1666V, the lightning would have had a larger voltage but most of the potential difference was 'spent' in the atmosphere.

 

From the link I posted in post #7, it states that lightening is 300 kilovolts.

How does the pathway affect the results? If Modest had been standing in a field and been struck directly, it would be a lot easier to calculate, but if the lightening came through the fan, then it had to have hit the house first, traveled through the electrical system and then jumped to his ear to complete the ground. How can that be factored in? Is it insignificant?

 

If air is so resistive, then is it not a factor of humidity? Modest, was it raining and/or humid at the time?

[Jay-qu]

I dont know if my thinking is entirely correct, but what I am imagining is something akin to a serial circuit. Picture the clouds being the top positive rail, the air being a resistor and modest is sitting there grounded while holding onto the positive rail. In this circuit there is a potential difference between the clouds and ground of around 300kV, but since the bolt spends so much time in the air compared to inside modest, it takes the brunt of the voltage drop in this circuit.

 

This is a bit of speculation on my part..

[modest]

From the link I posted in post #7, it states that lightening is 300 kilovolts.

How does the pathway affect the results? If Modest had been standing in a field and been struck directly, it would be a lot easier to calculate, but if the lightening came through the fan, then it had to have hit the house first, traveled through the electrical system and then jumped to his ear to complete the ground. How can that be factored in? Is it insignificant?

 

If air is so resistive, then is it not a factor of humidity? Modest, was it raining and/or humid at the time?

 

It was raining out. 100% humidity. But, it was also warm and the air conditioning was running which probably effectively dried the air in the house. I would guess that humidity is a big factor in the conductivity of air.

 

But, I'm sure the house took most of the current. That is to say: I'm sure most of the current passed through the walls and pipes and whatnot, not to bother me at all. So, even knowing lightning's typical properties wouldn't necessarily help as we can't assume I was on the receiving end of all that.

 

I dont know if my thinking is entirely correct, but what I am imagining is something akin to a serial circuit. Picture the clouds being the top positive rail, the air being a resistor and modest is sitting there grounded while holding onto the positive rail. In this circuit there is a potential difference between the clouds and ground of around 300kV, but since the bolt spends so much time in the air compared to inside modest, it takes the brunt of the voltage drop in this circuit.

 

This is a bit of speculation on my part..

 

Yes, it seems that would have to make sense considering the voltage difference between endpoints on my body is necessarily less than the same distance in the air by virtue of my body having less resistance while, presumably, the same current passed through each. Voltage along each 'resistor' would be proportional to resistance—both having the same constant of current.

 

That's also why I was looking for the difference in potential between the fan and me. It would seem that would have to be a rather impressive number.

 

~modest