What happens to an electron in the electric field

[hikarigenzo]

Hi,im new here. Can you explain to me what happens to the kinetic energy of an electron when it is accelerated in a uniform electric field? My guess is it will go to the positive plate and loses kinetic energy because it isdoing work against the field. Can anyone clarify this?

Thanks

 

[ZealScience]

Firstly, welcome.

Why do you think that it is doing work against the field? Negative charge moving up potential is a decrease in potential energy, i.e. work is done to the electron as it is gaining kinetic energy.

 

[hikarigenzo]

I think maybe my basic is not strong enough. Correct me if I am wrong. The electric field direction is from positive to negative right? So the electron need to do work to go to the positive plate. Am i right?

 

[Drakkith]

No, electrons are negatively charged and are attracted to the positive plate. The direction the arrows in the field point in many pictures is meaningless. It could easily be the other way around and it would change nothing. It's simply that like charges repel and opposite charges attract.

 

[ZealScience]

I think maybe my basic is not strong enough. Correct me if I am wrong. The electric field direction is from positive to negative right? So the electron need to do work to go to the positive plate. Am i right?

Well, not really. You may work more on the defining formulae. The formulae for field strenth is F=qE. The negativity of q would mean that F would be positive alone the negative direction of E

 

[hikarigenzo]

Thanks for all the replies, so what happens to the kinetic energy and potential energy of it?

 

[ZealScience]

Thanks for all the replies, so what happens to the kinetic energy and potential energy of it?

Electrostatic potential decreases of course. Since there is no other force acting on the electron, all these potentials lost to kinetic. Actually, you mentioned accelerated in OP, so what's confusing?

 

[jim hardy]

I have to oversimplify, get a physical picture in myhead and then build up to the mathematical explanation. I think in pictures and envy folks whose mind jumps immediately to the formula.

If i correctly recall a physics class problem from forty++ years ago,
However many volts are across the plates responsible for the field, as it approaches the positive plate the electron's kinetic energy approaches that many electron-volts ..

here's a practical example that even I could follow.

http://wps.aw.com/wps/media/objects/877/898586/topics/topic07.pdf

old jim