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Physics 102 Electricity and Magnetism
A problem of practical interest is to make a beam of electrons turn a $90^{circ}$ corner. This can be done with the parallelplate capacitor shown in RiculeE P27.54.
An electron with kinetic energy $3.0 imes 10^{-17} mathrm{J}$ enters through a small hole in the bottom plate of the capacitor.
a. Should the bottom plate be charged positive or negative relative to the top plate if you want the clectron to turn to the right? Explain.
b. What strength electric field is needed if the electron is to emerge from an exit hole $1.0 mathrm{cm}$ away from the entrance hole, traveling at right angles to its original direction? Hint: The difficulty of this problem depends on how you choose your coordinate system.
c. What minimum separation $d_{ ext {mila }}$ must the capacitor plates have?