hiya 1) Some quotes from physics tutorial site: The above all makes sense. But this is where I get lost: Wouldn't it be more correct if instead we said: *The kinetic energy charge has was transformed from charge's potential energy, and this kinetic energy gets lost as charge goes trough light bulb?* The way I understand it, as electron moves trough electric field its potential energy is transformed into kinetic energy ( same way as potential energy of object falling towards the ground is transformed into kinetic energy W[k] ). And when this W[k] goes trough lightbulb, W[k] gets transformed into other types of energy. So, if two charged parallel plates are 1 meter apart and electron is put inside their EF at point A(near negatively charged plate), then once electron travels half the distance between the plates it will loose half of its potential energy In short, loss of potential energy depends on how much closer a charge is to its final destination ( compared to its initial position ) and not how much of this charge's kinetic energy a device like lightbulb has transformed into other kinds of energies ( light etc ). Correct? 2) The following text also makes it sound as if potential energy is not location dependent, but instead it solely depends on where the devices such as ligh bulb are located! Let me explain what I mean: Note - green thingy represents a light bulb and red is wire. The two boxes are positive and negative terminals. Please Register or Log in to view the hidden image! If potential difference is defined as how much closer charge is at point B ( compared to point A ) to its final destination ( final destination being positive terminal ), then how can there be potential loss resulting from current going trough the light bulb? I know there is loss of energy due to electrons passing trough the lightbulb, but since charge in point B is not at all closer to positive terminal then in point A, the kinetic energy ( the one electrons lost while going trough light ball ) was not created from potential energy. Actually, I'd say that no potential energy charge posseses has yet been transformed into kinetic energy? thank you
The wire extending from the + terminal to the bulb extends the charge to the bulb. All of the potential voltage will be measured across the bulb. Electron passing through the bulb will heat the filament and energy will be lost as heat. You seem to be mixing static charge and electric circuits; that's not an easy way to think of electric circuits.
vern is correct... you are very confused. the potential drops across each light bulb... because each light bulb.. acts.. like a resistor.. thus there are 3 light bulbs... and so 3 resistances... the voltage in any series curcuit... will always divide up its voltages relative to the resistance in the path of flow... i.e.. 10 volts.. and 3 resistors.. of any ohm.. all of equal value... then.. each resistor will have 3.33 volts across it... each will... the amount of current that will flow... will be desided by the value in ohms of the 3 resistors... if for example... they were all 1 ohm... then 10 volts... across 3, one ohm resistors.. they each still has 3.33 volts across them... but... because the ohm are now only 3 ohms.. and not 3 million.. the amps will thus be much higher... too high probubly. amps=volts/ohms volts=amps x ohms ohms = volts / amps none of which has to do with an electrostatic field across any plates... why??? because an amazing thing happens when electrons are made to flow in conductive metal wires.... the energy flow.. is in the form of a left hand spinning photon field, which is commonly reffered to as 'an inductive field'... this inductive field, is the energy flow.. and is thought to represent electron flow in the wire itself. but... inductive fields... form and move.. at light speed.. and electrons can never move at light speed threw wires.... ever.. therefore this field formation is closely involved with electron flow, and generated by it.. but it, as a field, moves well in advance of the actual electrons... a novel mystery. i believe i can explain it... but people say mean things when i do.. and not at my proposals... but at me.. my grammer and so forth.. so i hestitate. -MT
This statement doesn't quite make sense. Electric potential is not a property possessed by a charge, but by the electric field. A charge can move from a region of high potential to low, but it can't "lose" electric potential. The words "electric potential" here should be replaced with "electric potential energy".
Wouldn't it be more correct if instead of the above statement the text would say: *The kinetic energy charge has was transformed from charge's potential energy, and this kinetic energy gets lost as charge goes trough light bulb?* I'm confused why my text book would explain how loss of potential energy depends on the distance the force acts on a charge inside EF, and then in next chapter it would without any explanations ignore all of what it was said in the previous chapter and declare that loss of potential energy does not depend on the distance traveled by this object inside EF? In one chapter it was said that potential energy is location dependent, and in very next chapter it kinda negate that. This simply doesn't make sense. It's kinda like if object at some height above the earth would turn its potential energy into another type of energy without first falling towards the ground. You can't turn potential energy into anything but kinetic energy. It doesn't make sense! If loss potential energy indeed does depend on the distance and force acting on charge during this distance, then why in conductors potential energy won't follow natural laws and instead "act against its nature" ?
Field effects, hence capacitance and inductance, always come into play to some extent but in an ordinary electrical circuit it is the resistance that matters most, e.g. the voltage loss, hence the energy produced as the current flows through wires and bulbs. --- Ron.
Instead of thinking of the weight falling through the air, think of it slowly falling through thick molassas, without gaining any speed. All the potential energy is converted to heat, and the weight aquires negligible kinetic energy. This is very close to what happens in a resistance like a lightbulb. The mean free path between collisions is so small that the electrons aquire very little kinetic energy between collisions. Now in a "good" conductor something else is going on. (good depends on the resistivity of the material and the current load) All points in a contiguous piece of the wire are essentially at the same potential. Obviously, this isn't precisely true or current couldn't flow, but provided the resistors have much greater resistance than the wires, it is a good approximation and all energy loss can be taken to occur in the resistors. Lightbulbs in your curcuit.
boris16: I think you're misreading your book. The work done by the electric field E on charge q moving in the direction of the field lines is W = Eqd, where d is the distance the charge moves. Since the electric field is conservative, the work done is equal to the negative change of the electric potential energy of the charge. That is, the electrical potential energy of the charge q decreases by the amount Eqd. Since the electric potential difference is defined to be the electric potential energy difference per unit charge, then over distance d, the electric potential drops by the amount Ed. Yes, but you can rapidly convert the kinetic energy to some other form. For electrons moving in a metal, for example, the energy is converted to heat in collisions. That is why electrons passing through a resistor heat the resistor. I don't know what you mean by this.
LETS FACE ONE SIMPLE FACT... BORIS16... SOME BOOKS JUST SUCK....!!!!!!!!!!! some other books are great... go and find them. but dont trust wikipedia... i have found too many errors in it. i have also found alot of the confusion you describe in alot of books... books are all written by humans... and humans can always mess things up. all i can recommend is that you not limit yourself to that book, or ... for that matter.. any new modern book... there is something called 'strategic information'.. i.e. making it harder for people.. the average wacko.. to learn stuff... thats why books, year after year, teach you less and less. the best books i have ever read, and still have, are old books.. the best, and most informative, and CLEAR.. was a russian text book from the 50's. do you get my point? -MT
JamesR: You have played this same word game before. There is only one form of energy. It depends upon movement. Heat is just another word for movement of mass, such as atoms, molecules, etc. We are just playing with words if we hear you say that movement of some particle is converted into movement of some other particle. Movement of one particle can only be converted into movement of some other particle. Why are you trying to imply that movement of one particle can be converted into something other than movement of some other particle? Kinetic energy, the movement of one particle, can be converted into heat, the movement of some other particle, BUT IT IS STILL THE MOVEMENT OF A PARTICLE. TRY READING MY LIPS. OR, FOR THE FIRST TIME IN YOUR PROFESSIONAL LIFE, TRY READING A BOOK ABOUT PHYSICS.
It's nice to see that the insanity has continued unabated since I last checked in. Potential energies don't depend on movement, they depend on position. No, heat is just another word for energy transfer through a temperature gradient. "Movement of mass" is quantified by kinetic energy, not heat. And if you're talking about what it is that makes things hot at the microscopic level, then you're talking about internal energy (of which thermal energy is one form). But again, that's not heat. Heat isn't a form of energy, it's a mode of energy transfer. Also, heating need not be done by moving masses. It can be done radiatively, with (massless) EM waves. He isn't saying that, you are. Energy is being transferred from one system to another. The first system is the conduction electrons, and the second is the resistor. The electrons lose kinetic energy and transfer it to the resistor. The resistor doesn't move anywhere, it just gets hotter. One of the basic lessons of thermodynamics is that how you answer questions depends on how you define your system. If you define the resistor to be a system, then you consider the constituent particles to be internal to the system. If you're standing on the moon (where there is no atmosphere) and you fire a bullet straight upwards, it will reach its apex and stop momentarily. At that instant all of its energy has been converted into gravitational potential energy which is not associated with particle motion. You must really love the taste of your shoe. You're constantly shoving it into your fat pie hole.
Tom's most recent tirade, like all before, made no more sense than babbling. But then I realized what his confusion was this time. There really is a difference between energy and potential energy. And they are even called by different names, one being called energy and the other being called potential energy. This is so that we can always tell the difference whether someone is talking about one and not the other. If I want to talk about energy, I can speak of something that is moving and therefore able to do work by transferring movement to something else. Particles, photons, neutrinos, gravitons ( at least in fairy tales ) can move, thereby having energy, and can do work. If I want to talk about potential energy, I can talk about something that is not moving now, but can become moving. Something that is not moving now cannot do work now. However, if that thing becomes moving then it can do work. So, when I talk about all energy, I can talk about all things that are moving now and therefore can do work now. You have a clue that I am not talking about all those things that are not moving now. And if I talk about potential energy then you have a clue that I am not talking about all those things that are moving now. See how neat it is that I can talk about energy and anyone who is not a fool can know what it means? And also how I can talk about potential energy and likewise anybody who is not a fool can know what it means? If you are still confused about the difference, think about trees. I have several oak trees in front of my house. They are all about 60 feet tall, I guess, and about a yard in diameter. They are real. The only thing potential about them is that they are potential fireplace logs. I can find small acorns in my yard. I can call the oak trees "oak trees" and I can call the acorns "potential oak trees". If I am talking to you about oak trees, I would expect you to think about those large things with leaves, but not get them confused with the teeny tiny little potential oak trees. I would not expect to need to constantly define an oak tree to you as "an oak tree but not a potential oak tree". If I were patiently trying to teach a small child about such things, I probably would have to constantly be sure to say either "energy but not potential energy" or "potential energy, not energy associated with movement". What's that? Something that IS moving can have both energy and potential energy? I know that.
Did you notice that the term "potential energy" contains the word "energy"? What does that suggest to you? To me, it suggests that "potential energy" is a particular type of energy. Another type is kinetic energy.
You're so pathetic. Rather than admit that you are wrong, you simply do what you always do: Put words in my mouth. Kinetic temperature T is defined by: (Avg KE)=(3/2)kT Why you would assume that someone who has an advanced degree in physics doesn't know something from Physics I, I do not know. I'm not confused at all, you're just too stupid to understand what I wrote. But then again, there's nothing new there. No dipshit, potential energy is just a form of energy, just like kinetic energy is. An object that has only potential energy (in some frame) is not an object that has the potential to have energy. It has energy, and its energy happens to be of the type we label "potential energy". And the difference between kinetic and potential energy is exactly what I said it was: kinetic energy depends on velocity and potential energy depends on position. Of course, there are velocity-dependent potentials, but in general potential energy needn't depend on velocity at all. On the one hand you tell JamesR (who I am certain has a degree in physics or a related field) to go look at a textbook, and on the other hand you spout off all this mental sewage that doesn't even remotely resemble what you can find in a textbook. It just makes you look like a complete idiot, and it certainly doesn't do the author of this thread any good. James was doing just fine before you came in here and started slobbering all over yourself. Piss off and let the scientists handle the education. Moronic crackpots such as yourself clearly aren't up to the task.
Tom may, if he has a lucid moment, read, if he can, the textbook quote in my thread re kinetic temperature and continue his ranting and raving directed toward those who have vastly superior education credentials compared to his own.
