# Electron in a parallel plate capacitor - finding plate's magnitude

1. Feb 4, 2005

### vaxopy

The drawing shows an electron entering the lower left side of a parallel plate capacitor and exiting at the upper right side. The initial speed of the electron is 7.00×106 m/s. The capacitor is 2.00 cm long, and its plates are separated by 0.150 cm. Assume that the electric field between the plates is uniform everywhere and find its magnitude.

See the picture attached..

I dont really know how to start this.. (at all).

would i try to find the centripital force of the electron, and let that equal to the plates strength?

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2. Feb 4, 2005

### dextercioby

Write the second law of dynamics.There's no centripetal force involved.

Daniel.

3. Feb 4, 2005

### michaelw

but how do you find its acceleration?

4. Feb 4, 2005

### dextercioby

By identifying which forces act on the particle...??And then applying the second law of dynamics for the moving particle..??

Daniel.

5. Feb 4, 2005

### Staff: Mentor

Using kinematics. There is a uniform acceleration in the vertical direction; constant speed in the horizontal. Find the acceleration, then the force, then the field.