Freshwater: A Bonsell in the offing?

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One of the low points for the defense in Kitzmiller was the testimony of Alan Bonsell, who was President of the Dover Area District Board of Education at the time of the adoption of the policy that provoked the lawsuit. Specifically, his sworn testimony in a pretrial deposition was found to be seriously contradicted by his equally sworn testimony in the court. Though it ultimately came to nothing, Judge Jones went so far as to refer the matter to prosecutors for potential perjury charges. (See here and here for the pertinent testimony.)

Now a roughly similar situation appears to have arisen in the Freshwater affair. It centers around the process by which Zachary Dennis was burned with a Tesla coil, and Freshwater is contradicting himself about it in two sets of sworn testimony and a motion filed in federal court. I’ll describe them in separate sections, reproducing a good deal of the testimony for the flavor of what goes on.

First recall that there are three legal proceedings under way, the administrative hearing on Freshwater’s termination; a federal suit brought against the district, administrators, and Freshwater; and a federal suit brought by Freshwater against the Dennis family, the district, and sundry others (including a number of unidentified John or Jane Does). The first two are the focus here. This is a long post, with lots of quotations from various of the legal venues, but it should give a feeling for the problems Freshwater is creating for himself in his sworn testimony in the several proceedings.

A schedule note: The administrative hearing was supposed to resume November 17, but did not do so and has been postponed to Dec 10.

Administrative hearing testimony

First, there’s Zachary’s hearing testimony on May 7, 2009, under questioning by Freshwater’s attorney about how Freshwater used the Tesla coil on students’ arms. In his testimony, (Transcript XIX 5-7-09.pdf) Zachary described it this way. I’ve extracted pertinent parts from the transcript; there was a fair amount of shuffling around to set up a demonstration table with an overhead projector. Throughout the quotations in this section “Q” is R. Kelly Hamilton, Freshwater’s attorney, and “A” is Zachary.)


Describing how the Tesla coil felt on his skin, Zachary testified

4 A. My experience the first time it was applied to me was a
5 burning sensation. It left little tiny welt-like things, and
6 then it turned red. And it just felt like static electricity
7 shock but stronger.
8 Q. Referring back to your diagram, Employee Exhibit No. 61,
9 where did the application of the Tesla coil take place upon
10 you?
11 A. On the overhead.
12 Q. On the overhead. Using what’s going to be a blue
13 marker, I want you to mark on Employee Exhibit No. 61
14 precisely where you had the Tesla coil applied to you in John
15 Freshwater’s classroom.
16 A. (Witness complied.)
17 Q. And you circled the overhead?
18 A. Yes.

After some rearranging of furniture in the hearing room to represent the classroom with an overhead projector near the front:

22 Q. So Mr. Freshwater was standing behind the projector but
23 between his desk and the overhead projector. Correct?
24 A. Yes.
25 Q. Standing slightly off center to the right?

and then from succeeding testimony:


Q. Okay. So when you walked up, Mr. Freshwater is holding
19 the Tesla coil. Which hand is he holding the Tesla coil in?
20 A. Probably his left or right. I don’t know what hand.
21 Q. Well, it has to be left or right. Which do you think it
22 would be?
23 A. Most likely his left.
24 Q. So left hand?
25 A. Yes.

[SNIP]

7 Q. So at this point, what happens next? You approach.
8 Just tell me what happens next.
9 A. I put my arm like this.
(Laid his arm on the plate of the overhead projectors)
10 Q. Um-hum.
11 A. Then he put his arm like this.
(Indicating Freshwater’s arm was across Zach’s hand’wrist)
12 And then he took the Tesla coil and went up and down twice and across twice.

[SNIP]

23 A. Put your forearm here, and take this hand and go up and
24 down twice and across twice.
25 Q. Okay. Now, I’m holding this like a pen.
1 A. Go like this.
2 Q. Okay. Now, what you’ve just described this as is a fist
3 with a pen inserted into my fist. Correct?
4 A. Yes.
5 Q. Okay. You may touch me and just go ahead and
6 demonstrate. And this is the guy that matters right here.
7 A. Okay.
8 Q. So if you won’t mind standing right there for me,
9 demonstrate what occurred.
10 A. Okay. Down, like, about four inches, and up and down
11 and across and across. Kind of pulls his arm, lifted up his
12 arm. And I walked back to my seat.
13 Q. Walked back to your seat, and that was that?
14 A. That was that.

[SNIP]

Hamilton got a volunteer from the gallery to serve as Zach’s body double in the demonstration so Zach could direct.

8 Q. Zach, you get in whatever position you need to see.
9 A. Okay.
10 Q. Would you agree that the individual coming up just put
11 their right arm down? Correct?
12 A. Yes.
13 Q. Now, when they put their right arm down, Mr. Freshwater,
14 you said, used his right arm over your right wrist. Correct?
15 A. Yes.
16 Q. Now, when he put his right arm over your right wrist,
17 was his hand clenched or was it palm on your wrist
18 controlling your wrist?
19 A. I think it was clenched, not palm.

[SNIP]

2 Q. Okay. And at that point, did you feel like you could
3 pull away?
4 A. No.
5 Q. If you wanted to pull your arm out, did you feel like
6 you could or could not?
7 A. No.

So in Zach’s testimony we see him with his arm on the plate of the overhead, Freshwater with one forearm holding down Zach’s wrist with the Tesla coil in his other hand, and he makes two vertical swipes and two horizontal swipes with the Tesla coil on Zach’s forearm. The picture above is nearly identical to what Zachary described in his earlier testimony in October 28, 2008 (I’m not going to type out that transcript, too! I have images of the text that can’t be cut and pasted.).

Now consider Freshwater’s testimony in the hearing on October 28, 2008, late the same day that Zachary first testified. Freshwater testified that he did use the Tesla coil on Zachary’s arm:


Q. How did you do this? You heard Zach’s description. Do you disagree with that or agree with it? Zach’s description was, he placed his arm on the overhead projector, you held his hand with one arm and put a mark up and down and crossed with the other. That part is what I’m asking you about, not what you described it as [the daisy chain of students]. I’m going to ask you about that later. But the method by which you did it …
A. You’re – I’m not getting your question.
Q. I’m sorry. I asked you, is that accurate?
A. Is that accurate?
Q. I believe I said, do you agree with Zach’s testimony?
A. No.
Q. You tell us how you did it.
A. When? With Zach?
Q. Okay. Let’s start with Zach.
A. I do not remember to go into that detail.
Q. Okay. If you don’t remember, are you sure that Zach is inaccurate?
A. Is he inaccurate?
Q. In the way he described that you did it to him.
A. I don’t do it that way, so that would be inaccurate.
Q. How do you do it?
A. Zach mentioned one way, students holding hands I’m holding it –
Q. I’m talking specifically to Zach. Did you put–did you use this device on Zach Dennis’s …
A. Yes
Q. … arm?
A. Yes
Q. And did it leave a mark that you saw?
A. No.
Q. And how did you do it when you used it on Zach’s arm?
A. The student comes up and gives me their arm. And I just use the Tesla coil on them. And most of the time they pull away.
Q. Okay. And if you would hold their arm down they wouldn’t be able to pull away.
A. I didn’t hold his arm down.
Q. That wasn’t my question. If you hold their arm down, they won’t be able to pull away, would they? That’s my question.
A. If I held their arm down, would they be able to pull away? No.

Then a bit later:


Q. Now, when students come up and volunteer, does it ever leave a mark?
A. Does it leave a mark?
Q. When you’re dealing with individual students. I’m not talking about where you have them holding hands like there. But when you’re dealng with an individual student and you’re marking their arm or you’re using it on their arm, does it ever leave a mark?
A. Slight red, yeah.

And then a little later:


Q. Zach also testified that you indicated this would leave a mark like a tattoo of a cross for a short period of time.
A. I do not remember saying that.
Q. You’re seen the pictures?
A. Yes.
Q. And do you find that those are accurate depictions of Zach’s arm?
A. Are they? Yes.
Q. At various times this has been described as an X or a cross. Quote frankly, I don’t care which one it is at the moment. But did you ever describe that you put an X on students?
A. I do not remember saying anything about a cross.
Q. That wasn’t my question. My question is, Did you ever say that you puit an X on him?
A. Yes.
Q. Is an X a mark?
A. Yes
Q. And is it your position that you put an X on Zach and not a cross?
A. Yes.

So we have Freshwater conceding that he put a mark on Zachary’s arm, and he claims that it’s an X and not a cross. He disputes the accuracy of Zachary’s account of exactly how it got there, but he cannot remember specifically how he did it.

Freshwater Deposition

In mid-October 2009 Mr. Freshwater was deposed by the Dennis family’s attorney for their federal suit. Recall that the school district defendants settled their portion of that suit in August 2009 but Freshwater remains a defendant in it.

In the deposition Doug Mansfield, the Dennis’s attorney, questioned Freshwater about the incident.


After reading Freshwater’s testimony from the admin hearing:
Q. So in your previous testimony [in the hearing] you confirmed that this device would leave red marks on kids’ arms.
A. On myself. On me.
Q. Well, the question was asking about students, was it not?
A. Can you read that again, sir?
Q. “Question: But when you’re dealing with an individual student and you’re marking their arm or you’re using it on their arm, does it ever leave a mark?”
“Answer: Slight red, yeah.”
Did I read that correctly?
A. Yes, you read it correctly.
Q. And so your testimony then is – your testimony then was that yes, it would leave a red mark on a kid’s arm when you applied it to them. Is that true?
A. Like I say, I misspoke there. I’m talking about myself.
Q. Okay. You believe it would leave a red mark on your arm, right? That’s what you just said.
A. Yes.
Q. But you don’t think it would leave a red mark on a kid’s arm?
A. I’ve never – I haven’t seen red marks on kids’ arms, sir.
Q. Don’t you think if it left a red mark on your arm, it would. likewise, leave a red mark on a kid’s arm?
A. We need to back up. We talked about with me how many times I use it on myself.

[SNIP]

Q, You’ve seen pictures of the mark on James Doe’s arm,
A. Yes.
Q. And you saw those in previous testimony.
A. Yes, I saw them. I’m just trying to think when I saw the first one. Yes.
Q. Okay. And it’s fair to say, isn’t it, that at least as depicted in those pictures, and I understand that you dispute that you did that, but at least in those pictures the mark that appears on James Doe’s arm is in the shape of a cross, correct?
A. No.
Q. You don’t agree with that?
A. I don’t agree with that.
Q. What do you think that the mark looks like?
A. I’m going to – we keep talking about this mark –
Q. I’m simply asking –
A. No, let me put – can I say something, sir?
Q. No, you may not. If you have something to say –

MR. HAMILTON [Freshwater’s attorney]: If you’re going to let him answer the question, he was trying to answer your question.
MR. MANSFIELD: Well, he’s not answering my question. My question was a simple one. Would you read back my question, please? [Reporter read it back]

A. Like an X.
Q. Okay. When you applied the Tesla coil to James Doe’s arm, is it your testimony that you made a shape in the form of an X or a shape in the form of a cross?

MR. HAMILTON: I’m going to object at this time.

A. On advice of my counsel I invoke my Fifth Amendment right to be free from self-incrimination as the existing statute of limitation in this matter has not expired.
Q. Let me show you something from your testimony from your termination hearing. On page 403, line 6, Let’s go back to line 1. “Question: The various times this has been described as an X or a cross, I frankly don’t care which one it is at the moment, but did you ever describe that you put an X on students”? “Answer: I do not remember ever saying anything about a cross.” Did I read those two correctly?
A. Yes.
Q. The next line: “Question: That wasn’t my question. My question is did you ever say that you put an X on him?” “Answer: Yes.” Did I read those correctly?
A. Yes.
Q. The next question: “Is an X a mark?” Answer: “Yes.” Did I read those correctly?
A. Yes.
Q. The next question: “Question: Is it your position here today that you put an X on James and not a cross?” “Answer: Yes.” Did I read those correctly?
A. Yes.
[Several lines of back and forth in confusion]
Q. That wasn’t my question, sir. My question was your testimony at the time when you testified during your termination proceedings was that you put a mark on James Doe’s arm and not a cross. Is that correct?
A. Then I will have to say I misspoke there. I did not put a mark.
Q. Now today you’re denying putting any kind of mark on James Doe’s arm; is that correct?
A. That would be correct.

So in his hearing testimony he made a mark, and in his deposition he didn’t. When asked specifically about whether he put a mark on Zachary’s arm, he now takes the Fifth Amendment, which is his right.

Filing for Summary Judgment

The deposition didn’t get into the procedure Zachary described that Freshwater disputed. But there is one final document that was recently filed in the federal case that’s pertinent. On November 16, 2009, Freshwater filed for summary judgment for dismissal of the battery claim in the civil suit the Dennis family brought against him. In the section of that filing titled “Statement of Material Facts” there’s this paragraph:

Toward the end of class, Mr. Freshwater asked whether anybody wanted to see what the tesla coil felt like. Id. at 142. James testified that he was the last of five or so students to go up to the front of the class to have the tesla coil applied to him. Id. at 142-143. Prior to going up to have the tesla coil applied to him, James watched the other students get the tesla coil applied to their arm. Id. at 144. James witnessed the electric charge touch the other students’ skin. Id. at 145 The application of the tesla coil on the other students was similar to the application that happened to James. James volunteered by approaching Mr. Freshwater in the front of the class and placed his right arm on an overhead projector. Id. at 146-147. Mr. Freshwater used his left wrist and laid it on top of James’ right wrist and Mr. Freshwater took his right hand to guide the tesla coil on James’ arm making two horizontal lines and two vertical lines. Id. at 147-148. The application of the tesla coil on James skin lasted around five seconds. Id. at 148. The application of the tesla coil on James’ skin was similar to a “static shock” and “kind of burned a little bit and itchy.” Id. at 151-153.

In other words, while in his deposition Freshwater denied the accuracy of Zachary’s hearing testimony, in the motion for summary judgment it is described exactly as Zachary told it. In fact, the motion’s description of the process is drawn from Zachary’s deposition in the case – the Ids refer to that deposition. So Freshwater’s attorneys in the federal suit accept Zachary’s version for purposes of asking for dismissal of the battery claim. (Incidentally, Zachary’s version was also at least partly corroborated by another student in that class.)

I will freely grant that eyewitness testimony is far from the best evidence regardless of the deference the U.S. legal system gives it. I will also freely grant that human memory is subject to many vicissitudes. Nevertheless I find the contradictions and inconsistencies fascinating, just as a slow-motion train wreck is fascinating.

44 Comments

I thought you could only take the fifth and refuse to answer if you did not answer any questions at all. In criminal cases, you either have to refuse to answer everything, or you have to answer. Is it different in this type of situation? For reference, the source that I used to review my memory was http://criminal.findlaw.com/crimes/[…]crimination/

IANAL and haven’t the faintest idea. There are several lawyers who hang around here: Any of them know?

Not a lawyer, so also confused. I’m also a bit confused by the summary judgment thing. I thought that to have summary judgment one needed to argue in the form “even if we concede all factual claims we still win under the law” so are we sure that the statement from the request for summary judgment isn’t in some context like that.

Also have Badger’s issue. I thought you could do that in the middle of testimony but not if you then continue testifying.

“even if we concede all factual claims we still win under the law”

That, more or less, is the argument you make in a MSJ, and I think Joshua is probably correct. If the outcome of the case turned on who’s version is believed, then a SJ is not appropriate. So conceding what happened by using the plaintiff’s account is appropriate in this instance. What it means is that (at least according to the argument his lawyer is making in the motion) it could have happened exactly the way Zachary said, but Freshwater nonetheless still wins. One would have to read the whole Motion to know for sure.

I am a lawyer and the essence of a summary judgment motion is that there is no “question of fact” that prevents the court from ruling that the case should be dismissed. You don’t have to exactly concede all factual claims – you can show that some are irrelevant to the legal questions involved – but it is no surprise that Freshwater’s attorneys would cite the kid’s testimony as if it is true.

The 5th Amendment stuff is off-the-wall (in 30+ years of doing this, I’ve never seen a civil litigant do that). I’d need much more context to know what’s going on there.

I find the most fascinating part is the obvious squirming during the deposition in the civil suit with the attempt to somehow claim that it is illogical to infer that if it left a mark on an adult it couldn’t leave a mark on a student. Just arrest him already.

In my jurisdiction, if you plead the 5th in a civil case, the jury is instructed to presume that your answer would have incriminated you.

Wow David D., that seems wrong. Like, exactly the opposite of what the 5th amendment was supposed to accomplish.

***

What I find most fascinating is that in all three testimonies he concedes he’s applied the coil to multiple students. In my mind, whether it leaves a red mark is somewhat irrelevant - the conduct is irresponsible regardless of the outcome. Like a teacher taking a kid bungee jumping without the parent’s permission - the fact that the kid came though it without injury does not excuse what you did.

If the coil didn’t leave a mark, that doesn’t mean he was a responsible teacher, it means he was lucky.

“A Bonsell In The Offing” makes me think of “Bored of the Rings”:

“‘You mean,’ he whispered, ‘there’s a balrog in the woodpile?‘“

eric said: …whether it leaves a red mark is somewhat irrelevant - the conduct is irresponsible regardless of the outcome.

Exactly. Plus it violates the manufacturer’s instructions, which means the manufacturer thinks it’s a bad idea. They should get a manufacturer’s representative to testify, and use the device on a hot dog or something.

David D writes…

In my jurisdiction, if you plead the 5th in a civil case, the jury is instructed to presume that your answer would have incriminated you.

eric responds…

Wow David D., that seems wrong. Like, exactly the opposite of what the 5th amendment was supposed to accomplish.

Actually, it makes sense. The 5th amendment was meant end the practice of coerced testimony in criminal trials, a situation where the government is your opponent and it’s using all it’s power to deprive you of some liberty.

Civil trials are another matter, in those it’s typically citizen A vs citizen B, and the apparatus of government is present only as the court, ostensibly the objective trier of fact.

While you can, of course, lose a civil case, you can only be deprived of your stuff, not your freedom, which in the eyes of the law (and constitution) is a much less burdensome possibility.

Since civil cases often hinge on he said / she said arguments, one might reasonably argue that a plaintiff taking the position “I don’t want to answer any questions” does have significant probative value.

Very interesting, stevaroni. The reasoning seems sound. Does anyone know if this applies to civil cases in Ohio?

I’ve been following the case with others and it seems a little creative thinking is in order to reconstruct Freshie’s thought processes; entirely inadmissaable of course.

1.) i have a captive audience. 2.) god is watching and requires souls. 3.) tatoo the symbol of christendom upon these impressionable youth; and 4.) hey presto! instant selvation. 5.) Lie through your teeth when confronted with the facts.

god loves a liar.

John Pieret:

Early on, when Freshwater’s pastor/spokesman talked about opposing counsel being a ringleader in the conspiracy they were alleging to subpoena two people who were going to be on the termination review board (and hence try to disqualify them) and how Freshwater might be forced to take legal action against the board’s attorney, and Kelly Hamilton didn’t rule it out, my reaction was “you’ve got to be kidding me” - now that it’s more or less being done, what do you think? (Because I think Hamilton is looking to be censured, for starters).

RBH, where’s that going, btw?

Robert:

Arms and souls for my Lord Yeshua!

Robert van Bakel -

My personal guess as to how these minds work is more along these lines…

1) “I ‘think’ by kissing up and kicking down - truth is whatever some arbitrary source of authority that fits nicely with my biases says it is.”

2) “I gain emotional satisfaction by manipulating or dominating others into submitting to that arbitrary source of authority (no matter what their inner beliefs may be).”

3) “Kids are easier to manipulate and dominate.”

I have to say, I did find this exchange humorous..

Q. Okay. So when you walked up, Mr. Freshwater is holding the Tesla coil. Which hand is he holding the Tesla coil in?

A. Probably his left or right. I don’t know what hand.

Q. Well, it has to be left or right. Which do you think it would be?

eric said:

Wow David D., that seems wrong. Like, exactly the opposite of what the 5th amendment was supposed to accomplish.

***

What I find most fascinating is that in all three testimonies he concedes he’s applied the coil to multiple students. In my mind, whether it leaves a red mark is somewhat irrelevant - the conduct is irresponsible regardless of the outcome. Like a teacher taking a kid bungee jumping without the parent’s permission - the fact that the kid came though it without injury does not excuse what you did.

If the coil didn’t leave a mark, that doesn’t mean he was a responsible teacher, it means he was lucky.

Except that Bungee jumping does have a legitimate element of danger to it. Whether getting zapped by the Tesla coil also has a similar element of danger is an issue before the court.

Stuart Weinstein said: Except that Bungee jumping does have a legitimate element of danger to it. Whether getting zapped by the Tesla coil also has a similar element of danger is an issue before the court.

Would you need a permission slip to take a kid to a science museum where he/she might touch some equivalent device?

For activities outside the scope of normal teaching, parents have a say in what counts as “risky.” Unless you want to argue that zapping a student with a tesla coil is so normal that your typical parent should expect that its part of an 8th grade science class, I don’t see how you can defend his behavior as responsible. The risk could’ve been 0 and its still irresponsible to do it without getting permission.

Like bungee jumping, this is not an activity that would be expected in class. A reasonable parent might consider it risky, even if the risk is objectively low. That is why it is irresponsible not to get permission first.

eric said:

Would you need a permission slip to take a kid to a science museum where he/she might touch some equivalent device?

One imagines that the science museum would have a railing, and perhaps a docent or sign saying “Please do not touch the hissing ball of hot plasma”, you know, for those who might need such a warning.

My child has a pacemaker and has had one since an early age. Mr. F ADMITS he did not ask any students if they had such a device. This so-called experiment would have had serious repercussions for my kid. Eighth graders have been known to do some pretty foolhardy things in order to avoid being labeled “uncool”. Is this really the kind of atmosphere we want to promote in public schools?

stevaroni said:

eric said: Would you need a permission slip to take a kid to a science museum where he/she might touch some equivalent device?

One imagines that the science museum would have a railing, and perhaps a docent or sign saying “Please do not touch the hissing ball of hot plasma”, you know, for those who might need such a warning.

One of the confusions in this case is that newspapers and lawyers keep calling a Tesla coil an “electrostatic device.” It is not an electrostatic device: current flows as long as the tip is close to some route to ground. And it’s current flow that does the damage. Some people are confusing a Tesla coil with Van de Graaf generators that one often sees demonstrated at science museums – think of the pictures of girls with their hair standing on end. Tesla coils and Van de Graaf generators are different devices with different properties and different safety requirements. A Van de Graaf generator operating at the same voltage as a Tesla coil (~50Kv in the T-coil model at issue) is safe to touch because the only current flow is a tiny direct current flow that lasts for just milliseconds after the generator is touched. A T-coil at that same voltage is not safe because a high frequency (~500KHz) current flows continuously in the latter. Both the continuous current flow and the high frequency are relevant to the safety issues associated with Tesla coils.

Stuart Weinstein said:

Except that Bungee jumping does have a legitimate element of danger to it. Whether getting zapped by the Tesla coil also has a similar element of danger is an issue before the court.

Except that the manufacturer’s handbook stated quite clearly that the device should not come into direct contact with the skin. As a classroom teacher there are a variety of things you can do that might be “cool” and even learning opportunities (not seeing how this qualifies as the latter, but it does the former), but intelligent responsible teachers don’t implement these “techniques” because it is recognized that they pose an unreasonable hazard to the student.

I remember in middle school there was a kid who could, flat footed, do forward and backward flips. His classmates urged him to do it again and again. The teacher started to do the same, paused momentarily, and then intelligently had him attempt to do so on the mats that, had he botched the jump, would have provided at least minimal cushioning for the kid were he to land on his back, face-plant, etc.

Based on the lack of judgement shown by Freshwater in the testimony, I wouldn’t be surprised if he would have, like my classmates, urged the kid to “do it again!” without taking any such precautions.

Remember, it is a key part of the educator’s job to also provide protection and safety for the students in their care.

dogmeatib said:

Stuart Weinstein said:

Except that Bungee jumping does have a legitimate element of danger to it. Whether getting zapped by the Tesla coil also has a similar element of danger is an issue before the court.

Except that the manufacturer’s handbook stated quite clearly that the device should not come into direct contact with the skin.

Well, that pretty much settles it.

RBH said:

eric said:A T-coil at that same voltage is not safe because a high frequency (~500KHz) current flows continuously in the latter. Both the continuous current flow and the high frequency are relevant to the safety issues associated with Tesla coils.

Its PERFECTLY possible to be severely shocked by a Van de Graaf, if the capacitance of the top sphere is sufficiently high; on the other hand, it would be MUCH harder to be killed by a Tesla coil, because at these high operating freqencies, nearly all the current is carried through a very thin layer of skin.…So you end up with RF burns, which is where this whole mess originated, giving RF burns for fun.

Steve

eric said:

Stuart Weinstein said: Except that Bungee jumping does have a legitimate element of danger to it. Whether getting zapped by the Tesla coil also has a similar element of danger is an issue before the court.

Would you need a permission slip to take a kid to a science museum where he/she might touch some equivalent device?

For activities outside the scope of normal teaching, parents have a say in what counts as “risky.” Unless you want to argue that zapping a student with a tesla coil is so normal that your typical parent should expect that its part of an 8th grade science class, I don’t see how you can defend his behavior as responsible. The risk could’ve been 0 and its still irresponsible to do it without getting permission.

Like bungee jumping, this is not an activity that would be expected in class. A reasonable parent might consider it risky, even if the risk is objectively low. That is why it is irresponsible not to get permission first.

I don’t know where you live but if the school has any field trip I have to sign a permission slip. Doesn’t matter if it is to a science museum or to a watch the play “Mao’s last dancer”

Thus giving the parent the chance to consider any risk they think might be encountered.

Sure this device might be encountered in the class room normally but not in this manner. It is much the same as if the teacher took liquid nitrogen and used it in a way not prescribed. I expect my child to come into contact with things that are dangerous but I don’t expect the teacher to promote the improper use of dangerous items.

Steve Taylor said: Its PERFECTLY possible to be severely shocked by a Van de Graaf, if the capacitance of the top sphere is sufficiently high; on the other hand, it would be MUCH harder to be killed by a Tesla coil, because at these high operating freqencies, nearly all the current is carried through a very thin layer of skin.…So you end up with RF burns, which is where this whole mess originated, giving RF burns for fun.

Steve

Well, yeah, with sufficiently high capacitance that initial jolt, when the charge is transferred from a VdG generator, could be zippy. But it’s a one-off; once the static charge is transferred (milliseconds) the current stops. However, with a Tesla coil it doesn’t stop – there’s a continuous supply of current so it flows until the device is removed or turned off. That’s why calling it an “electrostatic” device is misleading.

And the “skin” that is germane to the RF skin effect in a human body (as distinguished from a metalic conductor) is reportedly on the order of 150 cm. So it’s not conducted at the surface of the (human) skin as it is in a metal conductor but is pretty much through the interior of the body, likely following good conducting paths (blood vessels and nerves?). It’s not entirely clear how reliable that Wikipedia article is, but I’ve seen an RF burn that was basically a tunnel of damaged tissue bored into a forearm (back in my Navy days, so I have no idea now of the frequency, just that it was RF).

An RF burn is the result of the heating of the skin at the point at which it makes contact with a conductor carrying a radio frequency alternating current.

Normally, contact with a single conductor will have no effect unless there is some reason for current to flow. As long as you have no other contact with something that will support current flow, you may safely grasp the “hot” wire of a mains circuit. (FSVO “safely.)

In the case of RF, however, the body of the person contacting the conductor can serve as an antenna (however inefficient) and thus a “path” for current flow is established without having to touch anything else. The skin is not notably low-resistance, and can undergo significant heating at the contact point(s).

It doesn’t take much. When I was building my Novice ham station in 1964, and in the process of learning about grounding and RF, I managed to find places in the shack that were “hot” when the transmitter was on and the effect of contact was essentially the same as it would have been had the wire been red hot – frying sound, smell of burning flesh, and pain. That was only a total of about 30 watts at a frequency of about 3.7 megahertz.

Burns through the interior of the body may occur with any sufficiently large current, whether AC or DC, so the internal ones wouldn’t actually be “RF burns” in the generally accepted sense.

Don’t RF burns only occur in a certain range of frequencies where your body corresponds to wavelength?

The skin depth can be estimated from

d = { 2/[(4 x pi x 10-7) x (2 x pi x f) x g] }1/2

where f is the frequency in hertz, and g is the conductivity in siemans (formerly mhos).

If this Tesla coil is like the ones with which I am familiar, it doesn’t emit a single frequency, but a spectrum of frequencies (more like a “splatter” of frequencies).

This is because the method of generating the frequencies is by means of a vibrating interrupter. This method produces roughly a square wave current in the primary; and that translates into a spectrum of frequencies in the high voltage secondary.

The capability to produce burns below the skin depends on how much power is contained in those particular frequencies that penetrate to those depths (see skin depth formula in my previous comment). This might be a significant portion of the total power contained in the entire spectrum of frequencies.

These things hurt; I have felt them.

Wheels said:

Don’t RF burns only occur in a certain range of frequencies where your body corresponds to wavelength?

Not necessary at all – anything that allows the body to appear as a sink for the RF energy will do – but I imagine that if you were to approximate a half-wave dipole with ground plane, you could get a better quality injury with a given level of power available.

The burn is the result of the I-squared-R loss at the point of contact. As mentioned above, it doesn’t take much at all to generate the required temperatures.

Mike Elzinga said:

The capability to produce burns below the skin depends on how much power is contained in those particular frequencies that penetrate to those depths (see skin depth formula in my previous comment). This might be a significant portion of the total power contained in the entire spectrum of frequencies.

That would be diathermy as opposed to simple heat generated at the point of skin contact by the passage of current through a fairly large-value resistor.

If only a few milliamps make the trip from RF source to human body (not at all unlikely when in contact with an RF source of any significant power), they are doing so through a resistance likely to be on the order of 50,000 to 150,000 ohms. So for a brief moment, we have a very small area of skin dissipating anywhere from 5 to 20 watts.

This will cause a surface burn exactly like what one would see if the wire were at the temperature of a soldering iron.

Shebardigan said:

If only a few milliamps make the trip from RF source to human body (not at all unlikely when in contact with an RF source of any significant power), they are doing so through a resistance likely to be on the order of 50,000 to 150,000 ohms. So for a brief moment, we have a very small area of skin dissipating anywhere from 5 to 20 watts.

I am not familiar with this device, but if it is an RF source the means of power transfer will be electromagnetic radiation not current conduction. Passing a few milliamps through the victim’s skin resistance would indeed generate a lot of power, but would require hundred of volts to drive it, which implies prodigious amounts of radiated RF anyway.

The victim is an attenuator not an aerial, like a piece of meat in a microwave oven (the frequency of which is chosen to be one well absorbed by water and fat). Some RF frequencies will be strongly attenuated by body tissue, others less so, in the same way some light might pass through a colour filter. Placing the transmitter close to the skin will localise the power dissipation. I’ve no idea what frequency this device radiates on, or how powerful it is, but one watt of absorbed power can boil about a 1/16 inch cube of tissue every second, so it does not need much.

Here we at last stray into an area in which I can actually claim some credentials: FCC First Class Radiotelephone Operator License (with Shipboard Radar endorsement) (1979; now called a GROL) and Amateur Extra Class License (1975), Chief Engineer at two broadcast stations, military and civilian technical instructor, &c. &c. In nearly fifty years of fiddling with RF, I’ve made enough mistakes to have direct and detailed knowledge of this particular matter.

Dave Lovell said:

I am not familiar with this device, but if it is an RF source the means of power transfer will be electromagnetic radiation not current conduction. Passing a few milliamps through the victim’s skin resistance would indeed generate a lot of power, but would require hundred of volts to drive it, which implies prodigious amounts of radiated RF anyway.

Thousands of volts, preferably. And thousands of volts may be available when an unterminated transmission line (or any other handy conductor) gets connected to the output of an RF source of any significant strength. Thousands of volts does not imply thousands of watts.

You are correct that large amounts of radiated energy would be required to produce the heating observed. Since large amounts of radiated energy are not seen to be involved, we find resistive heating a more persuasive explanation. (Radiated energy would heat a much larger area, and do so at greater depth. Again, diathermy is rather well understood. A band of frequencies near the US Citizen’s Radio Service allocation was once set aside for medical diathermy.)

The victim is an attenuator not an aerial, like a piece of meat in a microwave oven (the frequency of which is chosen to be one well absorbed by water and fat). Some RF frequencies will be strongly attenuated by body tissue, others less so, in the same way some light might pass through a colour filter. Placing the transmitter close to the skin will localise the power dissipation. I’ve no idea what frequency this device radiates on, or how powerful it is, but one watt of absorbed power can boil about a 1/16 inch cube of tissue every second, so it does not need much.

The human body can and does function as an antenna, generally a poor one; there are some commercial products that rely on this. Anyone who remembers fiddling with rabbit-ear television antennas can recall times when the only way a clear picture could be obtained was to hold on to one of the whips. (“OK, Son, just stand right there for a while.”)

However, it doesn’t have to be a very good radiator to sink enough RF to produce the current required to cook a square millimetre of skin. The fact that the effect observed (RF burns on human skin) happens over a small area, and is accompanied by other phenomena that one might not notice until the second or third such incident is strongly indicative of resistive heating, and deprecatory of a diathermy hypothesis.

Shebardigan said:

Here we at last stray into an area in which I can actually claim some credentials: FCC First Class Radiotelephone Operator License (with Shipboard Radar endorsement) (1979; now called a GROL) and Amateur Extra Class License (1975), Chief Engineer at two broadcast stations, military and civilian technical instructor, &c. &c. In nearly fifty years of fiddling with RF, I’ve made enough mistakes to have direct and detailed knowledge of this particular matter.

Heh.

Sounds like just another “argument from authority” to me.

Besides - were you there??!?!?!

Shebardigan said:

Thousands of volts, preferably. And thousands of volts may be available when an unterminated transmission line (or any other handy conductor) gets connected to the output of an RF source of any significant strength. Thousands of volts does not imply thousands of watts.

You are correct that large amounts of radiated energy would be required to produce the heating observed. Since large amounts of radiated energy are not seen to be involved, we find resistive heating a more persuasive explanation. (Radiated energy would heat a much larger area, and do so at greater depth. Again, diathermy is rather well understood. A band of frequencies near the US Citizen’s Radio Service allocation was once set aside for medical diathermy.)

There are several things going on with this device. The voltage, and frequencies, in the secondary are sufficient to ionize air molecules. Part of this is due to the strength of the electric field at the end of a fairly pointed tip; but another part is due to the fact that some of the frequencies excite some of the molecular vibration modes of the molecules in the air. This latter essentially makes make ionization due to high field strength easier for an RF field than for a DC field.

Once the air becomes ionized in the vicinity of the skin, a large part of the coupling of AC flow to and from the skin is through an ionized conduction channel as well as through the capacitive coupling between the tip of the Tesla coil and the skin.

At the higher frequencies in the spectrum of the Tesla coil, it is not necessary for a person to be “grounded.” There is enough capacitance in the human body that small amounts of charge can be transferred back and forth without the need for the “closed” path that would be required for DC.

Once a high frequency current is flowing back and forth between the tip and the skin (note: at any given half-cycle there is not much charge transferred; but it is transferred in a very short time) then IR heating is part of the phenomena taking place in tissue.

But the molecules in tissue also have many, many vibrational and rotational modes, some of which are excited. In addition, both capacitive and inductive effects in the tissue will “shunt” current at various frequencies through various paths. This will depend on the amount moisture on the skin as well as the details of the fluids and tissues in a given individual.

That latter point was brought home to me in my youth when I watched a bare-footed five year old grabbing onto an electric fence without any apparent awareness of the high voltage. I thought the electric fencer (called a “Weed Chopper” in those days) was down. So, I grabbed the wire as I stepped over the fence to go check; and got knocked on my ass.

stevaroni said:

Heh.

Sounds like just another “argument from authority” to me.

Besides - were you there??!?!?!

Heh indeed. If you’ve got it, flaunt it.

And, at least as far as third-degree burns are concerned, I was indeed there. At the time, I would have preferred to be elsewhere, feeling considerably less foolish.

Mike Elzinga said: That latter point was brought home to me in my youth when I watched a bare-footed five year old grabbing onto an electric fence without any apparent awareness of the high voltage. I thought the electric fencer (called a “Weed Chopper” in those days) was down. So, I grabbed the wire as I stepped over the fence to go check; and got knocked on my ass.

Aw, man. Totally off topic, but that reminds me of a pheasant hunting expedition during which my high school basketball coach took a leak on an electric fence. Purely amazing reaction!

Mike Elzinga said: There are several things going on with this device. The voltage, and frequencies, in the secondary are sufficient to ionize air molecules.

[snip]

So, I grabbed the wire as I stepped over the fence to go check; and got knocked on my ass.

To the topic of RF burns, I would observe that 3.7 MHz coming from a transmitter with 20 watts plate input is not gonna ionize diddly, but my inadvertent contact with an energised conductor was all it took to produce a very visible 3rd-degree burn and a pronounced odor of flesh being charred. I was not “grounded” in any sense, other than having a low enough RF impedance to permit substantial current to flow through a large resistor (the small area of my skin at point of contact).

Looking at the size of the injured area, performing some measurements with an ohmmeter and grabbing some other numbers from the books, I calculated that I had encountered something on the order of 150 watts/cm^2, which is three orders of magnitude greater than direct tropical sunlight. One would expect instant charring, no ions required.

I am learning a lot about deathrays today!

Shebardigan said:

To the topic of RF burns, I would observe that 3.7 MHz coming from a transmitter with 20 watts plate input is not gonna ionize diddly, …

It isn’t ionization due to these vibrational modes that is the issue. What this does is to make it easier for complex molecules to be reoriented enough for the high field strength to do the ionization. In very complex organic molecules, rotational and vibrational modes extend all the way from the infrared down to radio frequencies.

This reminds me of the ST radar sets on the fleet snorkel submarines after WWII. The 2J50 magnetron in those sets operated at about 8850 MHz. The 2J50 magnetron was also used in some of the early microwave ovens. Better, cheaper and smaller magnetrons are now used; and they are tuned more appropriately to cook food.

Mike Elzinga said:

This reminds me of the ST radar sets on the fleet snorkel submarines after WWII. The 2J50 magnetron in those sets operated at about 8850 MHz. The 2J50 magnetron was also used in some of the early microwave ovens. Better, cheaper and smaller magnetrons are now used; and they are tuned more appropriately to cook food.

The magnets were fun to play with; I once bumped a box of nickel shot off of a cabinet directly above a sizeable magnetron magnet. Not one ball reached the floor.

Anyhow, my point has been that no exotic heating modes are required to explain skin damage from contact with an RF-energised conductor beyond simple I^2 * R.

Entities should not be unnecessarily multiplied.

Nuf Ced. DE KL7F CL ES QRT.

I should also point out, as Shebardigan mentioned in an earlier post, microwave ovens and diathermy essentially heat by coupling energy from an RF field to the vibrational and rotational modes of molecules, especially complex organic molecules. There is no ionization involved in this process.

Just to link this with discussions that have taken place on other threads about entropy and the second law of thermodynamics, this type of heating is one of dozens of ways to increase the kinetic energy per degree of freedom of the constituents of a system.

Kinetic energy per degree of freedom is essentially another definition of temperature.

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This page contains a single entry by Richard B. Hoppe published on November 18, 2009 10:34 PM.

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