In a laboratory demonstration of electron diffraction
PHYSICS · Subjective · A Level · Physics · Particles and radiation · Particles and radiation
Problem
In a laboratory demonstration of electron diffraction, a well-defined intensity maximum is observed at a glancing angle of about 50∘ when the accelerating voltage is 54V.
(i) Calculate the de Broglie wavelength of the electrons at 54V.
(ii) If the accelerating voltage is increased to 81V, find the new wavelength.
(iii) Without performing a full angle calculation, predict whether the principal maximum will shift towards a higher or a lower glancing angle when the voltage is increased from 54V to 81V. Give a clear physical justification for your answer.