Answer: zero.
- A zero
- B a large value
- C a negative value
- D infinity
Correct answer: A. zero
Explanation: Photons are massless; they travel at the speed of light.
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.