When light of wavelength 400 nm shines on a metal surface, electrons are emitted with a maximum kinetic energy of 1.2 eV. If the light intensity is doubled while keeping the wavelength constant, what will be the maximum kinetic energy of the emitted electrons?

Core Concept

The photoelectric effect equation is K_max = hf - φ, where h is Planck's constant, f is the frequency of light, and φ is the work function of the metal. The maximum kinetic energy depends on the frequency (or wavelength) of the light, not its intensity. Doubling the intensity only increases the number of electrons emitted, not their maximum kinetic energy.