[8 points] Two square metal plates of edge length L are arranged parallel to each other a distance d apart (where L is much larger than d) and charged to equal and opposite magnitudes Q. An electron (mass m, charge −e) is fired through a small hole in the left plate, as shown. What minimum speed must the electron have as it passes through the left plate in order to reach the right plate? Express your answer in terms of Q, L, d, e, m, and any other constants.

Which statement is true if the refractive index of medium a is greater than that of medium b? a. total internal reflection is possible when light travels from air to medium b to medium a. b. total internal reflection is possible when light travels from medium a to medium b. c. total internal reflection is possible when light travels from medium b to medium a. d. total internal reflection is possible when light travels from air to medium a. e. total internal reflection is possible when light travels from air to medium b.