Homework Help: Electron's response to a oscillating Electric field.

1. Sep 12, 2008

Himanshu

1. The problem statement, all variables and given/known data

The problem is to find the motion of the electron of charge -e and mass m which is initially at rest and which is suddenly subjected to an electric field E= E0sin($$\omega$$t).

The following mathematical expression is safe and sound but I am having trouble with the Physics involved.

x=(a0/$$\omega$$)t-(a/$$\omega$$)sin($$\omega$$t).

where a0=-eE0/m.

The result x(t) is varying linearly as well as oscillating in time. This means that the electron is responding to the electric field in a manner which jiggling as well as drifting away.

That's against our intuition. A charge should respond in accordance to the electric field. So what is happening here.

My speculation is that the drifting motion is due to the inertia of the electron and that the motion was due to the initial electric field.

2. Sep 12, 2008

tiny-tim

Hi Himanshu!

(have an omega: ω )

Why isn't it just (a0/ω)cos(ωt) ?

3. Sep 13, 2008

Himanshu

I cannot understand. How does the above expression appears? Can you please elaborate.

4. Jun 2, 2010

OMFGanELITE

Don't mean to revive an old thread, but the physics behind this situation is confusing me as well. The acceleration is purely sinusoidal, varying with time, but the position somehow has a linear term in there as well as a sine. What's the physical explanation for this?