21.27 . CP An electron is pro- jected with an initial speed vo = 1.60 X 10° m/s into the uniform field between two parallel plates (Fig. E21.27). Assume that the field between the plates is uniform and directed vertically down- ward and that the field outside the plates is zero. The electron enters the field at a point midway between the plates. (a) If the electron just misses the upper plate as it emerges from the field, find the magni- tude of the electric field. (b) Suppose that the electron in Fig. E21.27 is replaced by a proton with the same initial speed vo. Would the proton hit one of the plates? If not, what would be the magnitude and direction of its vertical displacement as it exits the region between the plates? Figure E21.27 K 2.00 cm 下 1.00 cm

21.27 . CP An electron is pro- jected with an initial speed vo = 1.60 X 10° m/s into the uniform field between two parallel plates (Fig. E21.27). Assume that the field between the plates is uniform and directed vertically down- ward and that the field outside the plates is zero. The electron enters the field at a point midway between the plates. (a) If the electron just misses the upper plate as it emerges from the field, find the magni- tude of the electric field. (b) Suppose that the electron in Fig. E21.27 is replaced by a proton with the same initial speed vo. Would the proton hit one of the plates? If not, what would be the magnitude and direction of its vertical displacement as it exits the region between the plates? Figure E21.27 K 2.00 cm 下 1.00 cm