Which term refers to the emission of electrons from a metal when light shines on the metal?

• A. Electromagnetic radiation
• B. Quantum
• C. Photoelectric effect
• D. Frequency

Answer: (C)

The main concept here is the photoelectric effect: when light shines on a metal, electrons can be ejected if the photons carry enough energy. Light is made of particles called photons with energy E = hν, where ν is the frequency. For emission to occur, a photon’s energy must exceed the metal’s work function φ. If hν > φ, electrons are ejected and the excess energy becomes their kinetic energy, KE = hν − φ. If hν is below the threshold, no emission happens regardless of light intensity. Increasing light intensity raises the number of photons hitting the surface, so more electrons are emitted (above threshold), but it doesn’t change their kinetic energy. The broader terms don’t capture the specific emission process: electromagnetic radiation is general light, frequency is just a property of that light, and quantum is a broad idea about discrete units like photons. The phenomenon described is specifically the photoelectric effect.