Electron refraction
A parallel beam of electrons is moving with velocity v is incident normally on a thin graphite film of atomic spacing 1.2*10^10 m. The beam is diffracted through an angle of 11 degrees, where 2dsin theta=lambda, the wavelength value.
Calculate the wavelength, velocity v and the accelerating voltage needed to produce this velocity.
I found the answers to the first two correctly, 4.6*10^11m and 1.4*10^7m/s respectively.
I used eV=1/2 m v^2, to find the voltage.
V=(1/2*10^31*(1.4*10^7)^2)/1.6*10^19=612.5V answer is supposed to be 450V
Thanks!
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