ScratchMonkey

That's DC, the simple case. With AC, it's voltage equals current times impedance. Complex numbers are involved. And if the frequency gets high enough, even that rule goes out the window and you have to switch to Maxwell's Equations. It's similar to the progression from Newtonian physics of motion to relativity.

icky

I don't expect that you would find anything besides a purely resistive load in a human. Cyborgs living secretly among us may be the exception.

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Peace through fear... since 1947!

Embiggener

http://www.amnh.org/exhibitions/eins.../manhattan.php

"Einstein: A Security Risk

In July 1940, the U.S. Army Intelligence office denied Einstein the security clearance needed to work on the Manhattan Project. The hundreds of scientists on the projectwere forbidden from consulting with Einstein, because the left-leaning political activist was deemed a potential security risk. "


"Einstein and the Nuclear Age

Although he never worked directly on the atomic bomb, Einstein is often incorrectly associated with the advent of nuclear weapons. "

Kerostasis

Well, teachers will occasionally exaggerate their credentials just slightly. A guest speaker in one of my history classes told us that while he was in the Marines, he had been assigned to assassinate Jane Fonda during the Vietnam war. Apparently she didn't show up to the speech at which she was going to be shot.

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kilevvri1

Wow, that kinda debunks that.

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El_Gringo_Grande

here is a good video about tasers and how they work.

http://revision3.com/systm/taser

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Sen. John McCain (AZ) For President '08
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I’m not racists, I have republican friends.
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"The essence of tyranny is the denial of complexity". -Jacob Burkhardt
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"A foolish consistency is the hobgoblin of little minds" - emerson
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"People should not be afraid of it's government, government should be afraid of it's People." - Line from V for Vendetta

El_Gringo_Grande

Nope. 1 mA won't kill you. It just won't under most normal circumstances. Yes there are certain medical conditions that can be affected by lower levels of amperage and if the the current is directly applied to certain organs then death can occur. And electricity is a strange thing and anything can happen.

But I am almost positive that ~100 mA is the accepted amount of current needed to kill. http://www.physics.ohio-state.edu/~p...l_current.html

And as far as the static electricity thing. It is ohms law.

As scratch said simple resistance and impedance are different but ohms law can be used to do most of the calculations. After all at any one point in time ac is nothing more than dc. And if all you have is a simple resistor then the voltage drop over the entire AC cycle will be consistent. The body is mostly a simple resistor. Plus I think static electricity is DC.

So measuring my bodies resistance from left to right hand I see I now have about 115k ohms. Lets assume we have 50 kV in the static electricity. That comes to about .43 amps. Should be enough to kill me but doesn't.

The bodies resistance can vary widely. Down to about 3000 ohms (maybe even lower) under the worst of conditions. (Sick, dehydrated, open wounds, thin skin and very hydrated skin).

50k/3k = 16 amps. I have measured static electricity as high as 75 kvolts using an O-Scope. 75k/3k = 25 amps. Under the condition I am currently experiencing 75k/115k = about .65 amps. Pretty close to 1 amp.

Now when I get shocked I doubt all of that is going through my heart. As you said the path the current takes is very important. Much of that current is going to travel over my skin and the body part closest to ground will get the all the current as well.

But the most important thing is that it is almost instantaneous. It just doesn't last long enough to do any real damage.

But a person does experience a very large dose of amps when getting zapped by a static shock.

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Sen. John McCain (AZ) For President '08
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I’m not racists, I have republican friends.
---
"The essence of tyranny is the denial of complexity". -Jacob Burkhardt
---
"A foolish consistency is the hobgoblin of little minds" - emerson
----
"People should not be afraid of it's government, government should be afraid of it's People." - Line from V for Vendetta

TheFeniX

I didn't say 1 milli amp will kill you. I said "on the order of" can kill you. But we're splitting hairs. Minute differences in amperage is the difference between a tingle and death. That was really the point I needed to get across, and through tracking back through my post, I didn't do a good job at explaining it. That's my fault. 15 milliamps is all you really need to cause heart fibrillations and death, but that's most likely an extended electrocution.

It has been years since electrical safety class, but our teacher made sure to let us know that around 1/100th of an amp is when a single shock can get you killed.

There's something screwy in your calcs. As much as I loathe the scientific approach used by the Mythbusters, using a Van de Graff generator on the order of hundreds of thousands of volts, they could still only crank out about 20 milliamps. Are you taking into account the resistance of the air which is orders of magnitude higher than human skin?

You'd be better off directly testing for amperage during a static shock, because even an instantaneous discharge of 1 amp should leave at least some kind of burn on contact. Even on the accidental grounding of minor circuits (like the remote wire on my car radio), I've noticed brown dots where contact was made.

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El_Gringo_Grande

Well, the Van de Graaff has properties that keeps the current consistent for any voltage. That is why you don feel "shock" of static electricity even though the voltage is much higher.

And as far as the measurements, they had to take into account the air resistance. The o-scope measures the voltage it receives, it doesn't guess what the voltage is on the other side of the air gap.

I think we did measure amperage for various resistances. But the only thing that stuck with me is the voltage achieved. 75 kV sounds way more impressive than .5 amps.

Also consider that most of the time the potential is closer to 20-30 kV (or lower) in a static discharge. We had to work very hard to get that kind of build up. And when it did discharge it hurt. I mean really, really hurt. We did things like took off our boon-dockers and socks and wet our hands and feet to get the maximum effect. (I was in Electronics Technician "A" school and it could get boring. Add a bunch of nerdy 18-19 year old kids with cool things like Oscilloscopes and you get the above.)

__________________
Sen. John McCain (AZ) For President '08
---
I’m not racists, I have republican friends.
---
"The essence of tyranny is the denial of complexity". -Jacob Burkhardt
---
"A foolish consistency is the hobgoblin of little minds" - emerson
----
"People should not be afraid of it's government, government should be afraid of it's People." - Line from V for Vendetta

El_Gringo_Grande

Oh, and I don't think you would see a burn. A burn is caused by energy transfer. There just isn't that much energy in the short burst of current.

__________________
Sen. John McCain (AZ) For President '08
---
I’m not racists, I have republican friends.
---
"The essence of tyranny is the denial of complexity". -Jacob Burkhardt
---
"A foolish consistency is the hobgoblin of little minds" - emerson
----
"People should not be afraid of it's government, government should be afraid of it's People." - Line from V for Vendetta

Sirusblk

I don't think anybody's recommending we grab someone rather then taser them. I just think the taser should not be used in stead of talking things out politely. In a few videos we've found on youtube we've found people tasered instead of actually communicated with (no the guy from FS doesn't count).

The idea of a police officer saying "I don't have time for this!" and pulling out the taser is all too real. And I for one find that scary. Aren't we supposed to resolve conflicts with words if ever possible? If not, why the hell do we have negotiators?!

If we use our words everyone can leave in a relative win-win situation. Resorting to any force is a lose-lose situation for everyone, and should only be used under the most dire of circumstances. That's my whole point. The taser is an effective means to a forceful situation, not just any situation.

Zoopy brought up a good point, people are dying because of taser use in addition to other circumstances. Officers should receive training on situation awareness with use of the taser no? If officers are tasering victims and then cutting off their airways then it's the officer's fault. I'm not against tasers, only the people behind them that aren't using them properly. It's the whole argument with gun control. "Guns don't kill people, People do!" Same thing with tasers. Both the gun and the taser is a means to the end.

Also if we're comparing "battle scars" for when we got shocked. I was shocked between a TV and an ungrounded power outlet. I was young, 7 I believe, and although it was nothing, just thought I'd share

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Tarenth

The assumption here is that the police officer does have the time to talk out a situation with someone who is being rude, uncooperative, or hostile. Unfortunately, the opposite is true most of the time and also why we have negotiators since normal police just don't have the time to negotiate through situations most of the time.

You have a relatively small number of police officers working on an ever growing work load and while both are growing the work is outgrowing the officers. The way that most officers will approach work is stop perp -> take them in if needed -> move on to next. In short its less about preventing crime, but putting out fires in an effort to prevent crime. The more people that are caught, the less likely someone else will try the same stunt in the near future.

Its kinda like being a social worker...except you get shot at some times. Quite obviously if the theoretical sterotypical social worker spent an extra hour with their charges a lot of problems could be avoided. Ignoring of course that their case load makes it so that if they spend even 1 hour on a single case they would have to be doing 36 hour days 9 days a week.

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My sanity is not in question...
It was a confirmed casualty some time ago.

xTYBALTx

Maybe one day the cops will be so "busy" that they won't have time to actually request compliance before arresting people. They'll "only have time" to pull walk up and tase you. That'll weed those bastards with heart conditions out of the population mighty quick!

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Current Tybalt theme song: Mason v. Princess - Perfect

Sirusblk

And thus the justice system has served its purpose. By simply resorting to tasering everyone rather than talk it out we stop more crime right? Quantity beats quality.

Hurray for sacrificing our human rights for human rights sake!

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MagnaCentipede

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