1985 B3

An electron initially moves in a horizontal direction and has a kinetic energy of 2.0 X 10³ electron-volts when it is in the position shown above. It passes through a uniform electric field between two oppositely charged horizontal plates (region I) and a field-free region (region II) before eventually striking a screen at a distance of 0.08 meter from the edge of the plates. The plates are 0.04 meter long and are separated from each other by a distance of 0.02 meter. The potential difference across the plates is 250 volts. Gravity is negligible.

(a) Calculate the initial speed.of the electron as it enters region I.

(b) Calculate the magnitude of the electric field E between the plates and indicate Its direction on the diagram above.

(c) Calculate the magnitude of the electric force F acting on the electron while it is in region I.

(d) On the diagram below, sketch the path of the electron in regions I and II. For each region describe the shape of the path.