Physic Labs

Problem 3

Monochromatic light of frequency f=8.0×1014 Hzf=8.0\times10^{14}\,\mathrm{Hz} illuminates a metal with work function ϕ=2.0 eV\phi=2.0\,\mathrm{eV}. Use h=4.14×10−15 eV sh=4.14\times10^{-15}\,\mathrm{eV\,s} and elementary charge ee; neglect energy losses after emission. (a) Check whether electrons are emitted. (b) Find their maximum kinetic energy. (c) Determine the stopping-voltage magnitude. (a) Find the first requested quantity. (b) Find the second quantity. (c) Determine the final result and check its units. (a) Check the emission th (a) Check the emission threshold. (b) Find the maximum electron kinetic energy. (c) Find the stopping voltage and the metal’s threshold frequency.
hf>ϕ⇒photoemission occurshf>\phi\Rightarrow\text{photoemission occurs}
problems.proof.analysis

This equation expresses the physical law governing the system. It incorporates the stated constraint rather than treating the relevant quantities as independent.

problems.proof.pitfall. Check the sign convention and physical case carefully; do not use a formula for a different motion or geometry.