1. The problem statement, all variables and given/known data Two parallel metal sheets of length 10 cm are separated by 20 mm in a vacuum. A narrow beam of electrons enters symmetrically between them as shown. When a PD of 1000 V is applied between the plates the electron beam just misses one of the plates as it emerges. Calculate the speed of the electrons as they enter the gap. (Take the field between the plates to be uniform.) (e / m = 1.8 * 1011 C kg-1.) Answer: 6.7 * 107 m s-1. 2. The attempt at a solution I used 0.5 m v2 = e E → v = √ 2 * (e / m) * E = √ 2 * (1.8 * 1011) * 1000 = 18 973 665.96 m s-1. But this formula does not include the length of the plates and their separation. Not sure what to do next.