Answer: E 2 /(2m e c 2 ).
- A E
- B E/2
- C E<sup>2</sup>/(2m<sub>e</sub>c<sup>2</sup>)
- D 2E
Correct answer: C. E<sup>2</sup>/(2m<sub>e</sub>c<sup>2</sup>)
Explanation: For the photon, p = E/c. For a non-relativistic electron, K = p<sup>2</sup>/(2m<sub>e</sub>). Substituting p = E/c gives K = E<sup>2</sup>/(2m<sub>e</sub>c<sup>2</sup>).
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.