Answer: Einstein.
- A Einstein
- B Isaac Newton
- C Michael Faraday
- D Georg Ohm
Correct answer: A. Einstein
Explanation: Einstein explained it using the photon (quantum) idea in 1905.
In the photoelectric setup, light striking the metal plate ejects electrons that cross the evacuated tube to the collector, producing a measurable current on the ammeter.
Concept context
Photoelectric effect, de Broglie waves, Bohr's model, atomic spectra.