Define the work function of a metal.
The work function of calcium is 2.9 eV2.9\text{ eV}2.9 eV.
Calcium emits electrons from its surface when ultraviolet light is incident on it. Extremely intense yellow light produces no electrons.
Explain these observations in terms of photons and their energy.
Light from a laser is incident on some calcium in a vacuum. Electrons are emitted. The wavelength of the light is 280 nm280\text{ nm}280 nm.
Calculate the shortest de Broglie wavelength of the emitted electrons.
