Hello,

A couple weeks ago I was looking in Ripley's Believe It or Not. There was a little article and a picture of someone using a machine that electicity was coming out and it wasn't harming her/him (can't remember).

I tried to do a little research and as far as I got was I THINK (!!!) it was a machine invented by Telsa - for he experimented with hiqh-frequency electricity. It also said that high-frequency electricity doesn't harm our skin.

In The Prestige (the film) the machine that makes the main character clone him uses high-frequency electricity (my guess, for it does not harm the him).



What is this machine called?
Has anyone got any idea how much a machine like this would cost? (I am guessing quite a bit)
Why doesn't high-frequency electricity harm our skin?

Xaethia

Frequency is rate of cycle in AC. It isn't voltage or frequency that kills you it is amperage or current. Tesla's coil generated a high frequency, high voltage, very low current AC. Basically his coil is a resonant transformer. They can be obtained from various sources for modest amounts, but until you learn a LOT more about electricity than you show above, I would highly recommend you not use one.

Well... actually... High voltage with low amperage can kill you. Just like low voltage and high amperage. They are two sides of the same coin.
But for the most part... father is exactly right.

I own a Tesla coil that I built myself. I use it in an electric chair act that I perform with in our show the Dead Girl Circus. http://www.deadgirlcircus.com

And if you think it doesn't hurt... well you would be very wrong!
I have people touch me with a grounded rod while the voltage passes through me.
It hurts and leaves burn marks on me.
I once had the voltage go through my head.
That didn't feel good at all. My depression went away and I probably lost some memory, but I won't notice that.

Any way...
there is plenty of information on Tesla Coils on the internet.
They are pretty easy to build, but the parts, especially the capacitors, can be hard to find.

Randi

Cool.
Thanks

How about a Wimshurst spark generator? The capacitors are leyden jars you make yourself.


http://en.wikipedia.org/wiki/Wimshurst_machine


http://makezine.com/17/wimshurst/

http://www.makershed.com/ProductDetails.......96155605


http://www.instructables.com/id/Wimshurs......nerator/

Very interesting... thanks for the post.

Randi

My pleasure.

cheers

I'm not sure what you are thinking of - when you get a static shock, you are experiencing a very high voltage/low amperage flow of electricity. Other than the surprise and "snap", it is harmless. I don't remember the break-down voltage for dry air, but I fairly sure it is over 1000 volts. Yet, there is a point where the amperage may not be low enough.

John

You answered your own quetion.
I was just stating that just because the amperage is low doesn't mean that any amount of voltage can't kill you.

If you have a wide river flowing very slowly into a lake...
And you have a narrow river flowing very rapidly into a lake...
They both dump the same amount of water into the lake at any given time.
Two sides of the same coin.

Randi

Voltage will not kill you amperage will. It's the amount of amperage that can cause your heart to stop not the voltage. That's why people with pacemakers have to be so careful around electric current.

It is rare that anyone dies from a stun gun or taser however, there is enough amperage even there in some instances to kill you.

I don't recommend you test this to find out. There is a HUGE difference between amperage and voltage and one definitely kills. The other does not. It always takes the current (amperage) to do the killing. It's like sticking your tongue on a 9 volt battery. There is so minimal amperage that all it does is cause mild discomfort. However attach your tongue to a 12V car battery and you see a NOTICABLE difference if you are still alive to talk about it.

And that's the electricity lesson for today class.


Amperage = Death

Max

And you would be wrong.
If voltage can't kill you, there would be no danger signs that say DANGER HIGH VOLTAGE.
It's all about ohm's law.
This article says exactly what I have been saying.
http://www.allaboutcircuits.com/vol_1/chpt_3/4.html

And that's the REAL lesson for today.

Randi

Randi this is from your article. I studied electronics. DANGER HIGH VOLTAGE comes with high current (amperage) Which is what kills you..THE CURRENT

Harm to the body is a function of the amount of shock current. (AMPERAGE) Higher voltage allows for the production of higher, more dangerous currents. (AMPERAGE) Resistance opposes current, making high resistance a good protective measure against shock.


Helps to understand what you read.

Max

Electromotive Force(measured in volts) is the force that causes the electrons to flow through the circuit. The higher the voltage, the more electrons that are flowing. The more electrons flowing, the higher the current. The amount of current flow (measured in amperes) is directly proportional to the amount of voltage. It's like water pressure and gallons per minute in a water system. The higher the water pressure, the more gallons per minute. It takes about 100 to 200 milliamps of current flow to cause your heart to go into fibrillation.



I'd like to see that. Do you have a video? Did you know that the electric chair came about because of the war of the currents? Edison and his people went to great lengths to discredit Tesla and Alternating Current. They used to publically electricute animals to show the dangers of AC. Of course Edison wanted everybody to use DC electricity.

It also says...
The amount of current through a body is equal to the amount of voltage applied between two points on that body, divided by the electrical resistance offered by the body between those two points.
It helps not to just repeat what you have heard and actually know what you are talking about.
I studied electronics too! And I come from a family of elctronic engineers.
The fact that you say that voltage can't kill you, shows you do not know all the facts.
Voltage can kill you... most definately.
To think that you can raise the voltage as much as you want as long as the amperage is low, and it won't hurt you is.. Wrong!

Like I have been saying... voltage and amperage are two sides of the same coin.


And we did a show last night where I did the elctric chair and it was filmed.
So I will have some footage soon.

To confuse things even more: Actually it's the amount of power delivered (which is the product of voltage and amperage) that does the damage. A very high static voltage, with no current (an 'open'; I=0) does not do any damage (c.f. Van de Graaff generator). Similarly, a high amperage without any voltage (a 'short'; V=0) doesn't "hurt" anything either (c.f. a perfect superconductor, which does not heat).

But in a practical sense Max is right in saying that it's the current flowing that ultimately does the damage to your body, because your body has a high resistance, so a power is generated if a current flows. But the only reason that current is the criterion is because we generally use voltage sources. If you'd use a current source, the voltage it is able to apply would be the criterion. And this depends on the amount of power available from the generator.

Often the voltage source is hooked up on the power net, which, if there is no weak fuse in between, can easily generate enough power to kill you.

Randi, I'd love to see the footage of your show, by the way!

(As we are throwing around credentials: I've a PhD in Electrical Engineering and work in medical research) (But I'm only an amateur magician )

I too have a degree in Electrical Engineering. I have several Tesla Coils and an Electric Chair which I have performed many times. Enzo is correct in that it is power that destroys tissue. However that power is computed by multiplying current times resistance (of the tissue). But the voltage will determine how much current goes through the resistor, that's all. It has no other influence.

In order to be electrocuted, it is generally necessary to get this current in the vicinity of the heart. This generally does not happen with a Tesla coil because of what is commonly known as the skin effect. High frequency energy tends to flow on the surface of the resistor, rather than the core. This effect becomes more pronounced as the frequency increases. This makes Tesla coils less dangerous than they would seem to be. One would not normally "play" with a 60 cycle source of 15,000 volts. I can play with 15,000 volts because it is high frequency. On the other hand, if you have a 3 inch spark jump off your finger, there is a small patch of skin ( ie Surface) that is damaged and hurts like HELL. I wore a conductive glove when I did that bit. That spread the current flow over a less concentrated area and the resulting pain was negligible.

Viano

Why do people keep repeating the same thing each one of us has said with just different words?

Father said...
"Frequency is rate of cycle in AC. It isn't voltage or frequency that kills you it is amperage or current."

The I said...
"Well... actually... High voltage with low amperage can kill you. Just like low voltage and high amperage. They are two sides of the same coin.
But for the most part... father is exactly right."

My whole point was that if have 100 billion volts at 10 milliamps, expect to die!
You can't increase the voltage to the nth level and expect it to stay safe as long as the amperage is low.

I said...
"If you have a wide river flowing very slowly into a lake...
And you have a narrow river flowing very rapidly into a lake...
They both dump the same amount of water into the lake at any given time.
Two sides of the same coin."

Which is saying the same thing as, with out the talk of being hurt...
"A very high static voltage, with no current (an 'open'; I=0) does not do any damage (c.f. Van de Graaff generator). Similarly, a high amperage without any voltage (a 'short'; V=0) doesn't "hurt" anything either (c.f. a perfect superconductor, which does not heat)."

Who is argueing with who here?
I never sid that amperage is not the part that damages you.
I just said that just because the amperage is low, doesn't mean electriciy can't kill you.
If you don't believe me, come to my home and I will hook my telsa coil up to either side of your heart and let's see what happens!
Which then goes on to...
"In order to be electrocuted, it is generally necessary to get this current in the vicinity of the heart."

I have been trying and trying to stop argueing on forums like these, but people read what they want to read and just force you too.
I am so sick of this.
Read people!
We are all pretty much on the same boat here!

Randi

Without getting drawn in to the argument I'd like to relate a story from one of the old-timer telephone techs here.

He made the good point that while everyone worries about the amps, you still need enough voltage to 'push' the current through your body

(Or as Randi Rain says)


Apparently there was a nice trick that the telephone technicians used to do with the apprentices..

They had massive battery cells that were quite low voltage, capable of delivering hundreds of amps for long periods (apparently they had warning labels on the sides stating such fact).

For a laugh, they'd chuck a small screwdriver or a spanner across the terminals, they'd glow - super hot, and sometimes even melt.

Then for a bigger laugh, they'd instruct the apprentice to pick up the batteries by the terminals (they always refused), so the old timers would demonstrate their super powers by doing it themselves.

The resistance of the metal was low enough that the current flowed quite happily between the terminals.
The resistance of the human body on the other hand was high enough that the current when flowing between the fingers was in the order of a few mA.

I'm sure a good time was had by all..

Cheers,
Monkey.

Good point, Viano. Didn't think about the skin effect.


What will happen: a current much higher than 10mA, because, again, low currents won't kill you. Much you say is true, but I really must insist on this small point.

Given a person holding electrodes in a specific way and therefore having fixed body resistance, the current will increase with the applied voltage, and therefore higher voltage will mean higher current. The only mistake you keep making is in saying that "100 billion volts at 10 milliamps" will kill someone. This is simply not true. Let's put aside the fact that the example you give is quite impossible to create (since the breakdown voltage of air is about 3 million volts per meter and therefore in your example the arms of the person holding the electrodes would have to be 33,000 kilometers (3/4 of the circumference of the earth) apart to prevent the current from passing through the air) and take more realistic "high" voltages in the order of MV. In this case it is perfectly possible to prevent harm by decreasing the current. You simply increase your body resistance, for instance by wearing isolating shoes, or standing on a platform with isolating feet (this only works of course if you only touch a single electrode and let the current flow to earth, rather than to a second electrode), or by limiting the total amount of available power, so the current will only flow for a very brief time (as in static shocks, or Van de Graaf demonstrations).

If you still don't believe me, here's a couple of excerpts from the
WikiPedia page on high voltage:

"Voltages of greater than 50 V applied across dry unbroken human skin are capable of producing heart fibrillation if they produce electric currents in body tissues which happen to pass through the chest area"

and

"Low-energy exposure to high voltage may be harmless, such as the spark produced in a dry climate when touching a doorknob after walking across a carpeted floor."

and

"Also, physics demonstration devices such as Van de Graaff generators and Wimshurst machines can produce voltages approaching one million volts, yet at worst they deliver a brief sting. These devices have a limited amount of stored energy, so the current produced is low and usually for a short time"

So, again, it's not the voltage, not the current, but the combination of (relatively) high current for a (relatively) long time that will kill you.

Best,
Enzo

Well... You can't use wikipedia as any example. There is inaccurate information all over that place.

Let me tell you this...
I do not have a degree in electricty, but I do in nursing.
The heart works by electricity. In the heart is the AV nodes.
They put out an electric pulse, based on carbon dioxide in the blood, to make the muscle that is the heart pump.
If you put electricty over these nodes you can interupt the charging of the AV nodes.
You put my Tesla coil over your heart it can quite easily send you into A fib, or even worse V fib.
Oddly enough, another charge could start you back up.

So I will leave you with this example.
People have died from being electricuted with a stun gun.
It happened to a person in Dallas not too long ago who was stung by a police officer.
So that means it is possible to die from high voltage and low amperage.
And there is no argueing with that.

Randi