Answer: 2.0.
- A 1.5
- B 2.0
- C 1.67
- D 2.5
Correct answer: B. 2.0
Explanation: Einstein's equation gives K<sub>max</sub> = h(ν - ν<sub>0</sub>). Initially K<sub>1</sub> = h(8 - 5) × 10<sup>14</sup> = 3h × 10<sup>14</sup>. Finally K<sub>2</sub> = h(11 - 5) × 10<sup>14</sup> = 6h × 10<sup>14</sup>. Therefore K<sub>2</sub>/K<sub>1</sub> = 2.
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.