[Roadam]

Imagine one negative charged plate and one electron(also negative) charging towards it. The electron doesnt have as much enegy to penetrate the field and hit the plate. What happens? Does electron just slows and backs away? Or does it completely stop? What is happening with the energy of the electron and the plate?

[anglepose]

i am nnot certain but i think the electrons energy is absorbed or dipursed by the negativly charged plate

[Tim_Lou]

the electron would slow down, get repelled back and move far far away from the plate. it will reach a velocity higher than the initial one, and continue to travel until interrupted by something else.

[UncleAl]

F=KqQ for an electron (test charge) approaching an infinite plane of charge. Work the two cases for q and Q having identical signs and opposite signs. Write the expressions for position, velocity, and acceleration as the system evolves over time. If you feel studly, include angles of approach and departure rather than orthogonal approach.

[Roadam]

Well if you could just explain me this american quotations. I am from Europe so...

Isnt it correct that if you would launch an electron from point where field of the plati is almost 0, it would have the same energy and veilocity when it would come back to that point?

How would energy of the plate change if the electron would receive energy?

[Tim_Lou]

if the plate is stationary, the potential at one point is always the same. since the energy of the whole system is conserved, the kinetic energy must be the same as well. it does not matter whether not the fields strength is zero or very great.

energy of the plate? what do you mean? well, if the plate is not stationary (not anchored) then it will accelerate and gain some kinetic energy (like the 2 body problem).

perhaps you mean the potential energy of the electron, it will decrease as it gains kinetic energy according to conservation of energy.

[Roadam]

I meant if plate is stationary and charged with the use of DC current. Would the electricity be used or created or niether? Does it really means only 2 body problem? Or would there be any change in charge?

[Tim_Lou]

the "electricity" will be used. The field does work on the electron, which accelerates. All the potential energy will turn into the kinetic energy of the electron as the electron escapes to infinity.

i think you are getting into the idea of capacitor, right? i don't think it is equivalent though since there is on way to "hook" the electron up or include it in a circuit. anyway, in a capacitor, there should be positive charges and negative charges. yeah, you can remove the postive plate and have a negative plate, but it wouldn't be a capacitor (ok, you can imagin have the postive plate separated at an infinite distance... in this case, yes it is a capacitor but it is not very useful).

the charge of the plate would not change, assuming it is not grouned or anything. since charge must be conserved. nothing will happen to the plate as long as it is anchored and insulated.

[Roadam]

I didnt mean the capacitator. I am just trying to ask how would the charge of the battery be affected when electron gains potential energy. And what happens if you discharge the plate when electron gets closer(it loses kinetic enegy, gains potential energy) and then suddenly there is no point from where you could describe that potential energy. Does the battery gain some energy?

[ronthepon]

Originally Posted by Roadam

I didnt mean the capacitator. I am just trying to ask how would the charge of the battery be affected when electron gains potential energy. And what happens if you discharge the plate when electron gets closer(it loses kinetic enegy, gains potential energy) and then suddenly there is no point from where you could describe that potential energy. Does the battery gain some energy?

If it is an isolated system you talk about, then the charge will be siphoned off somewhere, and that charge will change the potential energy. Also, it takes work to move charge from place to place.

Eventually, total energy of the system will remain same.