A narrow beam of electrons each of energy passes through a thin polycrystalline foil…
PHYSICS · Single correct · A Level · Physics · Particles and radiation · Particles and radiation
Problem
A narrow beam of electrons each of energy 200eV passes through a thin polycrystalline foil and strikes a fluorescent screen kept behind the foil. What is most likely observed on the screen?
(a) A single sharp spot directly in line with the incident beam
(b) A pattern of concentric bright and dark rings
(c) Two bright spots symmetrically placed about the beam axis
(d) A broad circular bright patch whose intensity decreases smoothly outward with no dark rings