An Introduction to Modern Astrophysics · Problem 5.4
Telescopes — Carroll & Ostlie
Physics — Astrophysics · photoelectric-effect
Problem
The photoelectric effect can be an important heating mechanism for the grains of dust found in interstellar clouds (see Section 12.1). The ejection of an electron leaves the grain with a positive charge, which affects the rates at which other electrons and ions collide with and stick to the grain to produce the heating. This process is particularly effective for ultraviolet photons (λ≈100 nm) striking the smaller dust grains. If the average energy of the ejected electron is about 5 eV, estimate the work function of a typical dust grain.