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Re: all my freinds
Jonathan Luthje
Talk about argumentative - it's not about an opinion - it's about facts:
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The facts are that: - Some hackers deliberately break the law - although a small minority of them - The term "hacker" means the ability to reverse engineer and modify - a "service person" of software, if you like - this includes such things as MCU's, HTML, PC / Server executables or whatever - so it DOES have a relevance to electronics. In fact if anyone wants to learn to "hack" I would suggest learning to program an 8051 MPU/CPU first off to learn how assembly works and to learn where the registers and memory addresses are. - I quite often find the need to "hack" my own software - PIC / HC811 / Atmel / as well as PC based - if you can program and debug an MCU you are a hacker - *I* am a hacker - although I have never in my life illegally hacked into any software, web page or other system of which I did not have the right to - do you call me evil because of my capability to program and debug an MCU? Oooh ... perhaps I should go to jail - what's the charge? MCU programming ... should get life imprisionment for that one. - Damn right it's "close to home" - I'm guessing for more than just me on this list - it's not an ideallism, it's a developed skill that is coveted - it shows that you can use your brain. Have a nice day .... Jon ----- Original Message -----
From: "Lise Quinn" <lise@...> To: <Electronics_101@...> Sent: Tuesday, October 30, 2001 9:33 AM Subject: Re: [Electronics_101] all my freinds Whatever - I am not the one who went into a long diatrabe of OPINON ofwhat a hacker is. And to then state that I don't comprehend words and ideasyou didn't bother to say so until someone with an opinion different than yourfor these folks is crackers and not 'hackers' as the media portrays.than criminal.does bad things with computers. If they do bad things that ought to becondemned, not because they are hackers, or because there are hacking but becausethey are 'doing bad' things. If some carpenters stared going around breaking uphaven't a clue about the meanings of words and even less about ideas.time for their crimes.but should not be tarred with the same brush as those who do those things.penalty. This is not a death penalty offense. It should get a serious sentence, butthat it is not wrong or 'bad'way includeing graphiti.resource to help prevent future crime. |
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vacuum and charge
Mark Kinsler
Vacuum has an inherent dielectric constant, known as the permittivity of a vacuum (or of 'free space'.) It also has an inherent inductance, known as the permeability of vacuum. These are values you can look up. They are both very close to what we find in air at atmospheric pressure.
A vacuum capacitor does indeed store charge in its vacuum, odd as that may seem. They typically have very small capacitance values, just as we find in air-dielectric capacitors. The air doesn't store the charge in an air-dielectric capacitor, of course: you can blow the air out from between the plates and the charge will remain. There are lots easier ways to determine the electrical qualities of air at low pressures than the one suggested. While a balloon experiment would be fun, I've done the same thing with a small vacuum pump, my trusty ignition-coil high-voltage power supply and a suitably-rigged jelly jar. What you're looking for is something called the Paschen curve for air. One axis of the Paschen curve plot is the voltage and the other is the pressure--though I think that there's a provision for the electrode gap in there somewhere (memory fails at times.) It turns out that this curve is fairly linear near atmospheric pressure. The voltage necessary for arc initiation is lowest at a partial vacuum. It rises for very high vacuums and for very high pressures. M Kinsler 512 E Mulberry St. Lancaster, Ohio USA 740 687 6368 _________________________________________________________________ Get your FREE download of MSN Explorer at |
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Re: Charge Storage in Cap (capacitance 101) boundary="----=_NextPart_000_00BB_01C1608C.654BA9F0"
What if the material is different but the spacing and surface area
are the same? Is the capacitance value always the same? No, because the dielectric constant of the two materials may be different and the capacitance is directly related to the dielectric constant. And the dielectric constant is dependant on the dipole moment of the material. (see the previous posted link) What you said is true though. If you had a really good insulator that could be made ipmossibly thin without breaking down it would also make a good capacitor. --- In Electronics_101@y..., verhap@o... wrote: the oppositely charged plates. The differences in the field leads toThe purpose of the dielectric is to modify the field between different capacitances.
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FW: all my freinds
aconto
Grow up
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-----Original Message-----
From: Lise Quinn [mailto:lise@...] Sent: Monday, October 29, 2001 4:33 PM To: Electronics_101@... Subject: Re: [Electronics_101] all my freinds Whatever - I am not the one who went into a long diatrabe of OPINON of what a hacker is. And to then state that I don't comprehend words and ideas properly because I am an American! What childishness. And your right - none of this has anything to do with Electronics - but you didn't bother to say so until someone with an opinion different than your own says something. Maybe this is all too close to home for you guys. ----- Original Message ----- From: G Ramasubramani To: Electronics_101@... Sent: Monday, October 29, 2001 3:19 PM Subject: Re: [Electronics_101] all my freinds Lise, Just for argument sake, by calling all hackers evil I feel you are throwing out the baby with the bath water. (or something like that :-) It is people who abuse hacking who are doing wrong. The actual term for these folks is crackers and not 'hackers' as the media portrays. You do lock your house, don't you? By your argument, you should not lock your house also - forget about installing complex security equipment. And, finally, I don't think this topic comes under Electronics_101. To each one, his (or her) opinion. Rama ----- Original Message ----- From: Lise Quinn To: Electronics_101@... Sent: Monday, October 29, 2001 3:13 PM Subject: Re: [Electronics_101] all my freinds I have a right to disagree with you and I do, and I do so without calling you stupid. Boy that's some nationalistic comment, "because Americans haven't a clue about the meanings of words and even less about ideas" what pig-headedly childish remarks. I still say you romanticize and glorify a behavior that is nothing more than criminal. Lise ----- Original Message ----- From: Jim Purcell To: Electronics_101@... Sent: Monday, October 29, 2001 2:51 PM Subject: Re: [Electronics_101] all my freinds Lise, I think you glorify it too much. I'm neither glorifying hackers nor demonizing them. I'm pointing out that being a hacker doesn't automatically mean that you break into computers. There are hardware hackers, software hackers, network hackers, internet hackers. ALL are hackers, non is by the definition 'hacker' someone who does bad things with computers. If they do bad things that ought to be condemned, not because they are hackers, or because there are hacking but because they are 'doing bad' things. If some carpenters stared going around breaking up furniture, we wouldn't imply that all carpenters did that sort of thing, even if quite a few were doing it. A hacker's goal is most often to get around a security or licensing issue. You still don't get the point, HACKERS sometimes do that, not all of them. I'm beating my head against a stone wall, I know, because Americans haven't a clue about the meanings of words and even less about ideas. You can romanticize a thief all you want but they will still serve real time for their crimes. Not because they are hackers but because particular ones have done bad things. And I never romanticize hackers, not even the 'good ones' they are just people and those who do NOT break into computers are still hackers but should not be tarred with the same brush as those who do those things. And they don't look so cool behind bars. Our own government is considering equating web-defacing and Denial of service attacks to acts of terrorism. I agree that those who do damage or snoop with their computers should be punished. But the law being considered apparantly carries the death penalty. This is not a death penalty offense. It should get a serious sentence, but not death. Just because one did no harm after compromising a system doesn't mean that it is not wrong or 'bad' I agree, I have no sympathy for anyone who does intentional harm in any way includeing graphiti. I think the argument that such people give opportunities to create better security is very weak, Well, you know the old saying, It takes a thief.... Safe crackers have been hired to test new safe designed. And they have also gone into the security business. Who knows more about preventing crime but a successful criminal. AFTER they serve their sentences I think they are a good resource to help prevent future crime. Jim To unsubscribe from this group, send an email to: Electronics_101-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. To unsubscribe from this group, send an email to: Electronics_101-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: Electronics_101-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. To unsubscribe from this group, send an email to: Electronics_101-unsubscribe@... Your use of Yahoo! Groups is subject to |
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Re: all my freinds
Lise Quinn
Whatever - I am not the one who went into a long diatrabe of OPINON of what
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a hacker is. And to then state that I don't comprehend words and ideas properly because I am an American! What childishness. And your right - none of this has anything to do with Electronics - but you didn't bother to say so until someone with an opinion different than your own says something. Maybe this is all too close to home for you guys. ----- Original Message -----
From: G Ramasubramani To: Electronics_101@... Sent: Monday, October 29, 2001 3:19 PM Subject: Re: [Electronics_101] all my freinds Lise, Just for argument sake, by calling all hackers evil I feel you are throwing out the baby with the bath water. (or something like that :-) It is people who abuse hacking who are doing wrong. The actual term for these folks is crackers and not 'hackers' as the media portrays. You do lock your house, don't you? By your argument, you should not lock your house also - forget about installing complex security equipment. And, finally, I don't think this topic comes under Electronics_101. To each one, his (or her) opinion. Rama ----- Original Message ----- From: Lise Quinn To: Electronics_101@... Sent: Monday, October 29, 2001 3:13 PM Subject: Re: [Electronics_101] all my freinds I have a right to disagree with you and I do, and I do so without calling you stupid. Boy that's some nationalistic comment, "because Americans haven't a clue about the meanings of words and even less about ideas" what pig-headedly childish remarks. I still say you romanticize and glorify a behavior that is nothing more than criminal. Lise ----- Original Message ----- From: Jim Purcell To: Electronics_101@... Sent: Monday, October 29, 2001 2:51 PM Subject: Re: [Electronics_101] all my freinds Lise, I think you glorify it too much. I'm neither glorifying hackers nor demonizing them. I'm pointing out that being a hacker doesn't automatically mean that you break into computers. There are hardware hackers, software hackers, network hackers, internet hackers. ALL are hackers, non is by the definition 'hacker' someone who does bad things with computers. If they do bad things that ought to be condemned, not because they are hackers, or because there are hacking but because they are 'doing bad' things. If some carpenters stared going around breaking up furniture, we wouldn't imply that all carpenters did that sort of thing, even if quite a few were doing it. A hacker's goal is most often to get around a security or licensing issue. You still don't get the point, HACKERS sometimes do that, not all of them. I'm beating my head against a stone wall, I know, because Americans haven't a clue about the meanings of words and even less about ideas. You can romanticize a thief all you want but they will still serve real time for their crimes. Not because they are hackers but because particular ones have done bad things. And I never romanticize hackers, not even the 'good ones' they are just people and those who do NOT break into computers are still hackers but should not be tarred with the same brush as those who do those things. And they don't look so cool behind bars. Our own government is considering equating web-defacing and Denial of service attacks to acts of terrorism. I agree that those who do damage or snoop with their computers should be punished. But the law being considered apparantly carries the death penalty. This is not a death penalty offense. It should get a serious sentence, but not death. Just because one did no harm after compromising a system doesn't mean that it is not wrong or 'bad' I agree, I have no sympathy for anyone who does intentional harm in any way includeing graphiti. I think the argument that such people give opportunities to create better security is very weak, Well, you know the old saying, It takes a thief.... Safe crackers have been hired to test new safe designed. And they have also gone into the security business. Who knows more about preventing crime but a successful criminal. AFTER they serve their sentences I think they are a good resource to help prevent future crime. Jim To unsubscribe from this group, send an email to: Electronics_101-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. To unsubscribe from this group, send an email to: Electronics_101-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. Yahoo! Groups Sponsor ADVERTISEMENT To unsubscribe from this group, send an email to: Electronics_101-unsubscribe@... Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. |
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Re: all my freinds
Jim Purcell
Lise,
I have a right to disagree with you and I do, and I do so without calling you stupid. Boy that's some nationalistic comment,? "because Americans haven't a clue about the meanings of words and even less about ideas" what pig-headedly childish remarks.?I still say you romanticize and glorify a behavior that is nothing more than criminal.Jim |
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Re: Digest Number 134
Mike Gabbert
Date: Mon, 29 Oct 2001 10:29:40 -0600 theI'd like to know, myself, why people think that the charge is stored in ofdielectric. It's stored on the plates, the dielectric just facilitatesSorry, but the charge is stored in the dielectric. That's why the amount capacitance depends in part on the kind of dielectric. A conductor willnot store a charge, only provide a path for it. Insulators respond to thepotential difference and the atoms get distorted in the sense that some lose or gaincurrent stops, not so with insulators. The fact that I can't see how a vacuumstores a charge doesn't alter the fact that it is the dielectric that stores thecharge. My idea would be that the charge is stored in the electric field. This is enabled equally by the positive plate which gave up electrons and the negative plate which has an excess, a condition that would like a current to flow, but is prevented by the dielectric. Various types of dielectrics have different dielectric constants which would dictate the thickness or distance between plates to achieve the same result when comparing different types of dielectrics. The first poster says a dielectric "facilitates" electron transfer. It actually inhibits it. To facilitate would make it a conductor, and there would be no charge. mike g. |
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Re: Charge Storage in Cap (capacitance 101) boundary="----=_NextPart_000_00BB_01C1608C.654BA9F0"
The purpose of the dielectric is to modify the field between the oppositely charged plates. The differences in the field leads to different capacitances.A good dielectric allows you to bring the plates closer together without arcing. Capacitance is a function of plate area and plate gap. Larger plates or smaller gaps give you a greater capacitance. Once the gap breaks down, you've lost capacitance. Paul |
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Re: Charge Storage in Cap (capacitance 101)
No, no, not ganging up, I just wanted to see if anyone really knew.
I kind of know but it's been a while since I've had that class. Guess what, I didn't even have to dust off the old physics book because I found a link on line. I was right out the alignment of the molecules in the dielectric being the key but I learned _why_ it increases the capacitance. Take a look at: solidstate/dielect.htm You may have to cut and paste the link in two pieces to get the entire URL. It also answers the vacuum question too, "Capacitance is defined as the ability of two conductors to store a charge Q when a potential V is applied across them." It's all in the definition :) --- In Electronics_101@y..., Jim Purcell <jpurcell@w...> wrote: manifold,theWhat about the chemical difference causes the difference in theI haven't the foggiest. Hey you guys, you're ganging up on me/us. pro plates view seems to be backed by more horsepower, i.e. the |
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Re: Charge Storage in Cap (capacitance 101)
What about the chemical difference causes the difference in theIt has to do with the nature of the material. Plastics are good dielectrics because current can't flow through them easily. Metals make poor dielectrics because currents do flow through them. Of course this only holds until you reach the breakdown of the dielectric (measured in volts per inch). One experiment I plan to run next year is to measure the change in dielectric of air as the pressure changes. I'll send a balloon up to 100,000 feet with a high voltage source. A servo will adjust the spacing on the leads of this power supply and we'll photograph the resulting arch. A question to the group, does resistance relate directly to dielectric value? Paul |
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Re: all my freinds
G Ramasubramani
¿ªÔÆÌåÓýLise,
?
?? Just for argument sake, by calling all
hackers evil I feel you are throwing out the baby with the bath water. (or
something like that :-)
?
???? It is people who abuse
hacking who are doing wrong. The actual term for these folks is crackers and not
'hackers' as the media portrays.
?
???? You do lock your house,
don't you? By your argument, you should not lock your house also - forget about
installing complex security equipment.
?
??? And, finally, I don't think this
topic comes under Electronics_101. To each one, his (or her)
opinion.
?
Rama
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Re: Charge Storage in Cap (capacitance 101)
Jim Purcell
manifold,
What about the chemical difference causes the difference in theI haven't the foggiest. Hey you guys, you're ganging up on me/us. I can't say for certain about either view now. I only can say that the pro plates view seems to be backed by more horsepower, i.e. the people who support that view seem to have more complex reasons. Or maybe they know just enough more about the subject to bullshit better. I don't know. :-) Jim |
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Re: Charge Storage in Cap (capacitance 101)
G Ramasubramani
¿ªÔÆÌåÓýJim,
?
??? The purpose of the dielectric is
to modify the field between the oppositely charged plates. The differences in
the field leads to different capacitances.
?
Rama
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Re: all my freinds
Lise Quinn
¿ªÔÆÌåÓýI?have a right to disagree
with you and I do, and I do so without calling you stupid. Boy?that's some
nationalistic?comment, ?"because Americans haven't a clue about the
meanings of words and even less about ideas"?what pig-headedly childish
remarks.
?
I still say you romanticize and
glorify a behavior that is nothing more than criminal.
?
Lise
?
?
? ----- Original Message -----
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Re: Charge Storage in Cap (capacitance 101)
Jim Purcell
Doug,
If a capacitor can be made of two plates in a vacuum and the charge isNope, but I always thought that the charge was stored on the plates too, then my office mate where I was teaching electronics told me that it was stored on the dielectric. I guess I assumed he knew what he was talking about, he had a EE, I didn't, though I did wonder about those vacuum caps. He retired before I thought about it so I never got to ask him. Jim |
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Re: all my freinds
Jim Purcell
Lise,
I think you glorify it too much.
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Re: Charge Storage in Cap (capacitance 101)
What about the chemical difference causes the difference in the
dielectric constant? --- In Electronics_101@y..., Jim Purcell <jpurcell@w...> wrote: manifold,tubular,Here is a question to ponder about capacitance. DisregardingBecause the dielectric constant is different. If they are chemically etc.dielectric orHere's a hint, _very_ pure water is a good dielectric. It is justSo which side are you on as the real storer of the charge, plates? |