Physics

Physics

Problem

Photons of energy 5.5×10−19 J5.5\times10^{-19}\,\text{J} are incident on a metal whose work function is 2.0 eV2.0\,\text{eV}. Find the maximum kinetic energy of the emitted electrons in joules. (1 eV=1.6×10−19 J1\,\text{eV} = 1.6\times10^{-19}\,\text{J}.)
Intuitive explanation

This is the photoelectric effect—when a photon's energy exceeds the work function, the excess energy becomes kinetic energy of the freed electron. The key is converting everything to the same units (joules), then applying energy conservation: photon energy equals work function plus maximum kinetic energy. Watch out for the unit conversion on the work function.

Intuitive explanation

This is the photoelectric effect—when a photon's energy exceeds the work function, the excess energy becomes kinetic energy of the freed electron. The key is converting everything to the same units (joules), then applying energy conservation: photon energy equals work function plus maximum kinetic energy. Watch out for the unit conversion on the work function.

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