38.   An electron is released from rest at the negative plate of a parallel plate capacitor and accelerates to the positive plate (see the drawing). The plates are separated by a distance of 1.2 cm, and the electric field within the capacitor has a magnitude of

2.1 x 106 V/m. What is the kinetic energy of the electron just as it reaches the positive plate?

w0960

 

Conservation of energy gives us

 

 

E is negative as the electron is traveling against the direction of the field line.

 

 

 

 

 

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This page last updated on June 11, 2018