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Natural Science Forum / Physics / Relativity / June 2007electric and magnetic field drops and rise
how long it takes for an electric field E to drop from 100V to 5V (fall time, tf) how long it takes for tha same field to drop from 100V to 0V how long it takes for a magnetic field to drop from 6 Gauss to 0.7 Gauss how long it takes for tha same magnetic field to drop from 6 Gauss to 0.2 Gauss how long it takes for an electric field to rise from 5V to 100V (rise time, tr) > how long it takes for an electric field E to drop > from 100V to 5V (fall time, tf) [quoted text clipped - 10 lines] > how long it takes for an electric field to rise > from 5V to 100V (rise time, tr) Depends on the circuit. Look up RC and RL circuits in your nearest introductory physics book. PD > > how long it takes for an electric field E to drop > > from 100V to 5V (fall time, tf) [quoted text clipped - 15 lines] > > PD which question you are about ta not answer professor? i never knew that an electric field drop or rise have anything ta do with RLC circuits may _you_ should do tha introductory to that and anything else, otherwise you force me to send an undergraduate to teach you some physics you may eat a sandwich while you listening > > > how long it takes for an electric field E to drop > > > from 100V to 5V (fall time, tf) [quoted text clipped - 20 lines] > i never knew that an electric field drop or rise have anything > ta do with RLC circuits That's why you need to read your book on such things as "resonance frequency" or "oscillators" or "tuning". If you are transmitting a radio signal and your circuit is designed for 100 Hz, then the fields drop from maximum to zero in 1/4 cycle, or 2.5 msec. If you are transmitting at 1 MHz, the time is 250 nsec. If you are asking questions about transient effects, why that depends on the impedance in your circuit, which depends on (surprise!) R, L and C. Read your book. - Randy > > > > how long it takes for an electric field E to drop > > > > from 100V to 5V (fall time, tf) [quoted text clipped - 23 lines] > That's why you need to read your book on such things > as "resonance frequency" or "oscillators" or "tuning". what tha fok has oscillators and crap has ta do with that questions yoo fool > If you are transmitting a radio signal and your circuit > is designed for 100 Hz, then the fields drop from maximum > to zero in 1/4 cycle, or 2.5 msec. what circuit you fool, who is talking about circuits? its about tha foken field you moron, nobody mentioned electrons i got you too, now anybody will know that you are moron indeed > If you are transmitting at 1 MHz, the time is 250 nsec. transmitting megaherdzi is EM fool, not electric field, learn physics > If you are asking questions about transient effects, > why that depends on the impedance in your circuit, > which depends on (surprise!) R, L and C. no fool, no transients, but drops and rise in E-fileds, period ask your sister doing your RLCs, or PD are you two living together? > Read your book what book? popular mechanics?. > - Randy > > If you are transmitting at 1 MHz, the time is 250 nsec. > > transmitting megaherdzi is EM fool, not electric field, learn physics Do you have any idea what "EM" stands for? Are you trying to declare that there is no electric field or magnetic field an an EM wave? > > If you are asking questions about transient effects, > > why that depends on the impedance in your circuit, > > which depends on (surprise!) R, L and C. > > no fool, no transients, but drops and rise in E-fileds, period What E-field? Under what conditions? What is producing it and what is causing it to change? The answer could be 10 minutes or 1 picosecond. - Randy > > > If you are transmitting at 1 MHz, the time is 250 nsec. > > > transmitting megaherdzi is EM fool, not electric field, learn physics > > Do you have any idea what "EM" stands for? no, you tell me > Are you trying to declare that there is no electric > field or magnetic field an an EM wave? you are tha only foken one talking about EM here, you cant be that foken stoopid > > > If you are asking questions about transient effects, > > > why that depends on the impedance in your circuit, [quoted text clipped - 3 lines] > > What E-field? Under what conditions? What is producing what what E-field, a 100V E-field > it and what is causing it to change? The answer could > be 10 minutes or 1 picosecond. yaa, finaly you read the question, you are funny tell me more about the 10 minutes and the 1 pS > - Randy > > > > If you are transmitting at 1 MHz, the time is 250 nsec. > [quoted text clipped - 26 lines] > > tell me more about the 10 minutes and the 1 pS I already gave you examples of 2.5 msec and 250 nsec. 10 minutes: Charge a capacitor. Disconnect the wires. Let it discharge slowly on a humid day. 1 psec: Discharge the same capacitor with a piece of low-resistance wire. Now if you want some help with your homework question, copy the rest of the question and tell us what is producing these E and B fields and what is causing them to change. - Randy > > > > > If you are transmitting at 1 MHz, the time is 250 nsec. > [quoted text clipped - 31 lines] > 10 minutes: Charge a capacitor. Disconnect the wires. > Let it discharge slowly on a humid day. you are perplexing me has nothing to do with capacitor discharging your capacitor is full with charged electrons flowin out in humid air it is about fiels not electrons > 1 psec: Discharge the same capacitor with a piece of > low-resistance wire. [quoted text clipped - 3 lines] > producing these E and B fields and what is causing > them to change. are you sure you know what fields and a potentials stands for in math and physics? > - Randy > > > > it and what is causing it to change? The answer could > > > > be 10 minutes or 1 picosecond. [quoted text clipped - 9 lines] > > you are perplexing me You asked for an example where the answer could be 10 minutes or 1 psec. That's an example where the answer could be 10 minutes or 1 psec. The answer could also be anything in between, such as the previous examples I gave with 2.5 msec and 250 nsec. > has nothing to do with capacitor discharging Well, you haven't said what it DOES have to do with. Until you've asked the actual question, there isn't an answer. > your capacitor is full with charged electrons flowin out > in humid air Yes. So the discharge time could be very long. You could take 10 minutes for the E-field to decay from 100 V to 5 V. > it is about fiels not electrons Fields are caused by something. You haven't said what. Fields are changed by something. You haven't said by what. That something could cause the change to be fast, or slow, or not at all. > > 1 psec: Discharge the same capacitor with a piece of > > low-resistance wire. [quoted text clipped - 6 lines] > are you sure you know what fields and a potentials stands for > in math and physics? Yes. Now, reread your homework and provide the rest of the question, or give up. - Randy > > > > > it and what is causing it to change? The answer could > > > > > be 10 minutes or 1 picosecond. [quoted text clipped - 13 lines] > 10 minutes or 1 psec. That's an example where the > answer could be 10 minutes or 1 psec. no you said the drop in a E-field can take 10min or 1ps and i said that this is funny but tell me more > The answer could also be anything in between, > such as the previous examples I gave with > 2.5 msec and 250 nsec. these are electron discharges, has nothing to do with E-fields fall times > > has nothing to do with capacitor discharging > > Well, you haven't said what it DOES have to do > with. Until you've asked the actual question, there > isn't an answer. !? > > your capacitor is full with charged electrons flowin out > > in humid air > > Yes. So the discharge time could be very long. You > could take 10 minutes for the E-field to decay > from 100 V to 5 V who asked you about electrons? . > > it is about fiels not electrons > > Fields are caused by something. You haven't said > what. Fields are changed by something. You haven't > said by what. That something could cause the change > to be fast, or slow, or not at all. why is important who or what causes the E-field, it does not matter, reread the question > > > 1 psec: Discharge the same capacitor with a piece of > > > low-resistance wire. [quoted text clipped - 13 lines] > > - Randy i understand you now, you think that E-fields are filled up with electrons everybody please fok meeee what about a M-field, what is it filled up with? > no you said the drop in a E-field can take 10min or 1ps > [quoted text clipped - 5 lines] > > these are electron discharges, A charged capacitor has an E-field between the plates. > has nothing to do with E-fields fall times The charge of a capacitor has nothing to do with the E-field? Are you sure? When the charge falls to half, the E-field falls to half. When the charge falls to zero, the E-field falls to zero. The E-field between the plates is directly proportional to the charge. > > Yes. So the discharge time could be very long. You > > could take 10 minutes for the E-field to decay > > from 100 V to 5 V > > who asked you about electrons? You asked me about E-fields. I gave an example of a decaying E-field. In fact, I gave you four examples where E-fields are decaying. - Randy > > no you said the drop in a E-field can take 10min or 1ps > [quoted text clipped - 13 lines] > The charge of a capacitor has nothing to do with > the E-field? Are you sure? not in context of tha OP question tha RLC crap you brought it in > When the charge falls to half, the E-field falls to > half. When the charge falls to zero, the E-field > falls to zero. The E-field between the plates is > directly proportional to the charge nothin to do with OP question . > > > Yes. So the discharge time could be very long. You > > > could take 10 minutes for the E-field to decay [quoted text clipped - 3 lines] > > You asked me about E-fields. I gave an example no, is not about any examples, cant you read? forget capacitors and crap it is about E-fields fall and rise times it is about M-fields fall and rise times reread tha foken questions > of a decaying E-field. In fact, I gave you four > examples where E-fields are decaying crap and non-sense why are you sniping the rest and not answer the beautiful questions? do you mean that E-fields are filled up with electrons? why on the moon are you talking about electrons so much? > - Randy > > > no you said the drop in a E-field can take 10min or 1ps > [quoted text clipped - 15 lines] > > not in context of tha OP question Your original question had no context. It asked a generic question about E-fields. The answer can be anything at all, depending on the nature of what is causing the E-field to decrease. > tha RLC crap you brought it in ... is one example of a changing E-field. > > When the charge falls to half, the E-field falls to > > half. When the charge falls to zero, the E-field > > falls to zero. The E-field between the plates is > > directly proportional to the charge > > nothin to do with OP question Sure it does. Your question was about an E-field changing from 100 V to 5 V or 0 V. My answer involves an E-field that changes from 100 V to 0V. The time to reach 0 V can be 10 minutes. It's an E-field. It's decreasing. It reaches 0. The time can also be 1 psec. Or 250 msec. Or 50 years. The answer to your original question is: "10 minutes. Or 1 psec. Or 250 msec. Or 50 years. Depends." OK? > > > > Yes. So the discharge time could be very long. You > > > > could take 10 minutes for the E-field to decay [quoted text clipped - 5 lines] > > no, is not about any examples, cant you read? It's about SOMETHING. You just haven't specified what. > forget capacitors and crap > > it is about E-fields fall and rise times > it is about M-fields fall and rise times Which could be 10 min. Or 1 psec. Or 250 msec. Or 50 years. Depending. > reread tha foken questions > [quoted text clipped - 6 lines] > > do you mean that E-fields are filled up with electrons? Nope. I mean that E-fields could take 10 min to decay or rise. Or 1 psec. Or 250 msec. Or 50 years. Depending. > why on the moon are you talking about electrons so much? Doesn't matter. Let's just talk about E-fields. Q: how long it takes for an electric field E to drop from 100V to 5V (fall time, tf) A: Could be 10 minutes. Or 1 psec. Or 250 msec. Or 50 years. Depending. Q: how long it takes for tha same field to drop from 100V to 0V A: Could be 10 minutes. Or 1 psec. Or 250 msec. Or 50 years. Depending. Q: how long it takes for a magnetic field to drop from 6 Gauss to 0.7 Gauss A: Could be 10 minutes. Or 1 psec. Or 250 msec. Or 50 years. Depending. Q: how long it takes for tha same magnetic field to drop from 6 Gauss to 0.2 Gauss A: Could be 10 minutes. Or 1 psec. Or 250 msec. Or 50 years. Depending. Q: how long it takes for an electric field to rise from 5V to 100V (rise time, tr) A: Could be 10 minutes. Or 1 psec. Or 250 msec. Or 50 years. Depending. Is that better? By the way, E-fields aren't measured in "volts" but I haven't even bothered with that aspect of your question. - Randy > > > > no you said the drop in a E-field can take 10min or 1ps > [quoted text clipped - 114 lines] > I haven't even bothered with that aspect of your > question. volt per meter, or centimeter or millimeter etc, so what, it is a scaling factor, are you familiar with scalings, means nothen in a relativity group you are talkin about electrons in capacitors when the question was about E-field strength rate of change, one would presume minimums and maximums, in vacuum or whatever now tell me that i am stoopid if i now change the questions from E-fields and M-fields to G-fields, you and PD will ask me on what planet, atmospheric pressure, density and such then tell me that EM equal an E-field and a M-field twisted together what a waist of sperm > - Randy > > Q: how long it takes for an electric field to rise > > from 5V to 100V (rise time, tr) [quoted text clipped - 10 lines] > > it is a scaling factor, are you familiar with scalings, means nothen Means a lot. A 10000 Volt power line 100 m away from you is safe (E field = 10000 V/100 m = 100 V/m). The same line one mm away from you, you die. (E field = 10000 V/0.001 m = 10 million V/m, big spark, fire, death). Same voltage. > in a relativity group you are talkin about electrons in capacitors You asked an incomplete question about changing E-fields and B-fields, and you asked it in this group. > when the question was about E-field strength rate of change, one > would presume minimums and maximums, in vacuum or whatever > > now tell me that i am stoopid Nah, I'll let others decide that. > if i now change the questions from E-fields and M-fields to > G-fields, you and PD will ask me on what planet, atmospheric > pressure, density and such No, an analogous gravitational question might be something like this: "I have a tank with 100 gallons of water in it. How much time will it take to get to 5 gallons? How about 0 gallons?" > then tell me that EM equal an E-field and a M-field twisted together Not "twisted together", but each oscillating in its own plane: http://www.monos.leidenuniv.nl/smo/index.html?basics/light_anim.htm - Randy > > > Q: how long it takes for an electric field to rise > > > from 5V to 100V (rise time, tr) [quoted text clipped - 15 lines] > line one mm away from you, you die. (E field = 10000 V/0.001 m > = 10 million V/m, big spark, fire, death). Same voltage. no sh.t, you are blaverin about safety now, you are a kid > > in a relativity group you are talkin about electrons in capacitors > > You asked an incomplete question about changing E-fields > and B-fields, and you asked it in this group. incomplete? like yours charge proportional with voltage? half charge half voltage? please show me that capacitor having tha same capacitance at both 100V and 5V dQ/dt = C(E)dE/dt > > when the question was about E-field strength rate of change, one > > would presume minimums and maximums, in vacuum or whatever [quoted text clipped - 22 lines] > > - Randy > > > it is a scaling factor, are you familiar with scalings, means nothen > [quoted text clipped - 4 lines] > > no sh.t, you are blaverin about safety now, you are a kid No, I'm "blaverin" about the denominator of V/m. I'm telling you 10000 V/100 m is different from 10000 V/0.001 m, even though they're both 10000 V. The denominator is not just "a scaling factor means nothen", it's the difference between living and dying. Do you think the difference between living and dying is "nothen"? > > > in a relativity group you are talkin about electrons in capacitors > > > You asked an incomplete question about changing E-fields > > and B-fields, and you asked it in this group. > > incomplete? Well, as complete as my question: > > "I have a tank with 100 gallons of water > > in it. How much time will it take to get to > > 5 gallons? How about 0 gallons?" Is my question complete? What's the answer? > like yours charge proportional with voltage? In a capacitor, yes. Q = CV. > half charge half voltage? > > please show me that capacitor having tha same capacitance > at both 100V and 5V > > dQ/dt = C(E)dE/dt That is not a capacitor equation. This is: Q = CV. And yes, the capacitor has the same capacitance at 100 V and 5 V. If I buy a 50 uF capacitor at Radio Shack, I expect it to have C = 50 uF at 100 V and at 5 V. - Randy > > > > it is a scaling factor, are you familiar with scalings, means nothen > [quoted text clipped - 52 lines] > > - Randy the capacity for a capacitor you buy wherever is a function of both voltage, frequency, temperature and many other things, you professor, maybe your phd > > > > it is a scaling factor, are you familiar with scalings, means nothen > [quoted text clipped - 52 lines] > > - Randy take a look professor, page 4 http://docs-europe.electrocomponents.com/webdocs/0117/0900766b80117c46.pdf > > And yes, the capacitor has the same capacitance > > at 100 V and 5 V. If I buy a 50 uF capacitor at > > Radio Shack, I expect it to have C = 50 uF at > > 100 V and at 5 V. > > take a look professor, page 4http://docs-europe.electrocomponents.com/webdocs/0117/0900766b80117c4... Oh dear, are we dropping the brain-dead act momentarily to score points? OK, I learned something. Though a 30% capacitance variation from 0 to rated voltage sounds awfully large. Now can you answer my tank-draining question? > > > > "I have a tank with 100 gallons of water > > > > in it. How much time will it take to get to > > > > 5 gallons? How about 0 gallons?" - Randy > > > And yes, the capacitor has the same capacitance > > > at 100 V and 5 V. If I buy a 50 uF capacitor at [quoted text clipped - 5 lines] > Oh dear, are we dropping the brain-dead act momentarily > to score points? i dont know what i do, but sorry for that > OK, I learned something. Though a 30% capacitance > variation from 0 to rated voltage sounds awfully large. [quoted text clipped - 6 lines] > > - Randy area of the outflow, position, length of the sink ? i did this type of question with some variations many times before the idea is that to remember that the pressure at the bottom of the tank decrease with time the length of the sink is very important > > > Q: how long it takes for an electric field to rise > > > from 5V to 100V (rise time, tr) [quoted text clipped - 43 lines] > Not "twisted together", but each oscillating in its > own plane: nice, are you sure that what you have in an EM is an E-field and a M-field? are they in phase or in anti-phase? EM without oscillations is still EM? > http://www.monos.leidenuniv.nl/smo/index.html?basics/light_anim.htm > > - Randy |
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