Basic electricity problem.

  • #1

Homework Statement



Given an electric field ε V/m that is constant in the x-direction and a charge +q C located at the origin and free to move in the x-direction. (a) What is the magnitude and direction of the force F acting on q? (b) If q moves under the influence of F a distance d m, how much work is done by F? (c) Assuming the voltage at the origin to be zero, what is the voltage Vd at x = d m, bearing in mind that ε = -dv/dx? (d) How is the loss in electric potential energy related to the work done by F? (e) Assuming the charge has a mass m kg and zero velocity at the origin, show that the KE of the charge at x = d is equal to the loss in electric potential energy.

Homework Equations





The Attempt at a Solution



a. F= εNq in the positive direction
b. W=Fd
c. I can guess that it's -εx but I don't know how to explain it properly
d. Equal by conservation of energy.
e. Not too sure how.

Thank you in advance.
 

Answers and Replies

  • #2
35,264
11,519
a-d: right.
For (e), I would use energy conservation. Alternatively, calculate the acceleration, and use this to determine the velocity there.

The question uses an ugly way to deal with units :(.
 

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