Answer: hf - phi (work function).
- A hf, ignoring the energy needed to escape the metal surface
- B hf - phi (work function)
- C phi - hf, with the terms in the reversed (negative) order
- D hf/phi, dividing instead of subtracting the work function
Correct answer: B. hf - phi (work function)
Explanation: Photoelectric equation: KE_max = hf - phi. Energy of photon minus work function gives kinetic energy of emitted electron.
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.