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- billricardi, on 04/13/2009, -0/+584Layman's terms: Electrical potential is a way to measure how much static voltage exists between two points.
In order to do the math on this, you need to arbitrarily pick a place where the potential energy is zero.
So said student said: Hey, I'm going to put that arbitrary 0 point RIGHT where you want us to measure! So the answer is 0! Lol!
Hope that helps. :) - b3owulf, on 04/13/2009, -1/+302I'm glad the teacher actually gave him credit for the answer
- OUPablo, on 04/13/2009, -5/+295hire that man now. He knows how to think outside the box
- jake1337, on 04/13/2009, -18/+289LIKE A BOSS
- semperfidoordi, on 04/13/2009, -6/+273If I had a dime for everytime I ***** my way through an answer on a test.
I'd have about 90 cents. - BlackSheep720, on 04/13/2009, -4/+213can someone explain in layman's terms?
- Jarrane, on 04/13/2009, -0/+195Save that money. You'll need it later.
- fanfablebig, on 04/13/2009, -9/+190I don't think i have a high enough I.Q. to laugh at this.
- Addaone, on 04/13/2009, -2/+18099 times out of 100 a test like this would state that electric potential is 0 at infinity, but this test didn't so the student exploited a loophole.
- terracottapai, on 04/13/2009, -0/+159Being a history major, I'd have at least 20 bucks.
- DavidTurnbull, on 04/13/2009, -1/+153I just laugh anyway to blend in.
- terryhuang, on 04/13/2009, -6/+126Genius
- MrSpam, on 04/13/2009, -0/+115He put a spell on it.
- Grym11, on 04/13/2009, -0/+114On an Organic Chemistry test once I didn't know the answer so I just drew a random molecule. You can imagine my surprise when it turned out to be the exactly right one. I still maintain that I sub-consciously knew the answer...
A buddy of mine, for his Spanish final in highschool put ABACADABA (aba-ca-daba) over an over and walked out of the test. He later found out that he got an 85% for his final and a passing grade for the class. Lucky bastard. - Disease, on 04/13/2009, -2/+116lol english
- peteyb1313, on 04/13/2009, -2/+97That teacher Chose some Random words to capitalize
- whahaa, on 04/13/2009, -4/+89fire this man now. he's a party pooper.
- orangederange, on 04/13/2009, -11/+92i have no idea what this all means, potential something. but the handwritings look quite similar.
- ripple123, on 04/13/2009, -0/+81he moved the box to a particulary convinient frame of reference, i think you mean
- fanfablebig, on 04/13/2009, -2/+81Your assumption makes you look pretty ignorant.
- AYOTTERIOT, on 04/13/2009, -1/+67in my E+M class we're told that if it's unspecified, the reference voltage is at r=∞
- RcFromTwitter, on 10/10/2009, -1/+66Watt great jokes you guys have.
- BC200, on 04/13/2009, -3/+65Speedy thing goes in, speedy thing comes out.
- Shmebber, on 04/13/2009, -5/+66Being an English major, I'm beginning to feel a little left out...
- inactive, on 04/13/2009, -1/+60http://xkcd.com/451/
- scarz99, on 04/13/2009, -5/+64That's what she said.
- TheVirus, on 04/13/2009, -0/+59Reference Voltage is my safe word in my S+M class.
- Nairebis, on 04/13/2009, -2/+54Don't worry, you can digg up the past participle jokes that the engineers won't get. :)
- michelsonmorley, on 04/13/2009, -1/+46Most of my teachers would have marked me wrong for that. It doesn't matter if it would be correct or arguable; it wouldn't be the answer that they wanted. And I'd probably roll over and take it.
- spiralspirit, on 04/13/2009, -3/+41both the answer and his reasoning (work) were correct - so full marks.
- charlie6969, on 04/13/2009, -1/+38dugg for being able to send to an engineer friend of mine.
I didn't get it.lol I do now. Thanks, billricardi. - offrdbandit, on 04/13/2009, -0/+37"Yeah because a written test is an accurate representation of a real life situation in any way."
College isn't training for "real life situations" - it's education. - blackblackberry, on 04/13/2009, -3/+39I agree... what a shocking answer.
- inactive, on 04/13/2009, -1/+36he just hacked the gibson
- bhays2010, on 04/13/2009, -9/+43This teacher's comment was absolutely electrifying.
- dlan4327, on 04/13/2009, -1/+34Random capitalization is what makes the world great.
- Fozefy, on 04/13/2009, -0/+29Most times you'd get a couple points since he's showing he understand whats going on to some extent (obviously not completely has he didnt do the problem), looks like he got 4/7.
It was obvious what the teacher wanted him to do, so using the one "non-interesting" answer is gutsy. - RobbieSan, on 04/13/2009, -10/+39Future grad student.
- inactive, on 04/13/2009, -0/+26HE'S A WITCH!
- illcider, on 04/13/2009, -7/+33Guess I'll give it a shot. First off, another common name for "Electric Potential" is "Voltage", yes the same ones on your batteries. Basically, given a charge distribution (say for simplicity 1 electron), all points in space will have an "electric potential" associated to them. As far as the physical significance is concerned, however, only the DIFFERENCE in electric potential really matters, because that is what is used in problems concerning how much work is done when moving a charge. Think of it like this, if you have a stationary electron, it would require work to pull an proton away from it. Furthermore it would require more work if you wanted to move the proton to a further place. It's the same as lifting an object a distance away from the ground, the higher you want it, the more work needs to be done. In the case of lifting a mass, however, the quantity you are concerned with is "potential ENERGY", whose units are different from "Electric Potential" (energy/charge). The real benefit of electric potential is that it does not rely on the charge you are moving, only the stationary charge(s).
Now on to the problem at hand:
First of all, the image shows that this is "part c" of a problem. Given its nature, I imagine the problem is a picture with some distribution of charge on a coordinate axis. Now in 'part c' the student is asked to calculate the potential of a point, assuming he is given some distribution of charge. In most cases, you would assume that the potential of a point infinitely far away from the system of charges is 0, this is usually reasonable because a charge infinitely far away would experience negligible influence from the distribution at hand. The convenience of this is purely mathematical, i.e. the work required to bring in a charge from infinity to a point (say x=a y=a as in the problem) would just be the electric potential of that point multiplied by the charge (remember we are concerned with differences in electric potential here, and since we take infinity to be 0, the difference is just the value at that point). This of course, applies to moving from one point to another within proximity of the charge distribution as well, i.e you just take the difference between the points to get the change in voltage (from here you can multiply by the charge you moved to get work done). However since the problem does not specify that the potential at infinity is 0, you can technically assume that the whole system is under some kind of giant electric field originating at infinity that negates the potential at (a,a) due to the charge distribution, causing it to be 0. It is convenient for the problem at hand, however, not practical. For example, if there was a 'part d' to the question that asked "What is the work required to move an electron from the point (x=a,y=a) to the point (x=b,y=a)?" you would still have to find out the electric potential at (a,a) and (b,a) with respect to 0 at infinity. - quickgold192, on 04/13/2009, -3/+29...or high school physics
- jacesKINGS, on 04/13/2009, -1/+27See, originality like this sends a bolt of energy through my spine.
- DeadlyAlpaca, on 04/13/2009, -3/+29Summary: don't take electrical engineering. You'll find these like this amusing.
(Like I did) - landrypants, on 04/13/2009, -3/+27way too much writing dude
- aTroll, on 04/13/2009, -0/+24cuz let's face it- If we're not even accepted by our fellow diggers... :-(
- Velnich, on 04/13/2009, -1/+24Was I the only one to get the gist of the joke here without fully understanding the mechanics?
This reminds me of the fabled "Why Hitler?" Exam question and it's "Why not?" credited answer. - RoboRay, on 04/13/2009, -1/+24The student shows a lot of potential, also.
- grantmoore3d, on 04/13/2009, -0/+23Good thing that professor didn't give him any resistance
- billricardi, on 04/13/2009, -4/+27I dunno if they're great, but they have 'potential'!
BOOM! Full circle! =) -
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