A test charge is located inside the electric field produced by a pair of oppositely charged metal plates.
Which of the following combinations best describes how the force on the test charge and the electrical potential energy ( Ep ) of the test charge vary with its distance from one of the plates?
a. Force = constant; Ep = constant
b. Force = constant; Ep = proportional to distance from one plate
c. Force = proportional to distance from one plate; Ep = constant
d. Force = proportional to distance from one plate; Ep = proportional to distance from one plate