A scanning electron microscope uses a uniform15.0 kN/C electric field to acceler
ID: 2226120 • Letter: A
Question
A scanning electron microscope uses a uniform15.0 kN/C electric field to accelerate electrons horizontally toward the subject to be imaged. After traveling 5.0cm the electrons are accelerated to a speed of 1.62*10^7m/s. The next step is to deflect the electrons so that they can scan across the sample. To accomplish this, the electrons are directed between a pair of oppositely charged parallel plates, which produce a uniform electric field of 6.42*10^3N/C perpendicular to the electron beam. This field extends for 3.5cm along the electron's path. A.) For the scanning electron microscope above, find the electron's vertical displacement. B.) What would the electron's vertical displacement be if the scanning electric field were reduced to 3.14*10^3N/C?Explanation / Answer
a) the amount of time that the electron be inside the two plates.T=3.5e-2/1.62e7=2.16e-9(s).the acceleration rate.a=E*q/m=6.42e3*1.6e-19/9.1e-31=1.13e15(m/s2).so S=a*T^2/2=2.6e-3(m).b) then a=3.44e3*1.6e-10/9.1e-31=6e14(m/s2).so S=1.4e-3(m)