Answer: Hydrogen-like (one-electron) atoms.
- A All atoms in most cases under typical conditions
- B Multi-electron atoms according to standard textbooks
- C Hydrogen-like (one-electron) atoms
- D Molecules mainly in general practice
Correct answer: C. Hydrogen-like (one-electron) atoms
Explanation: Bohr model: works for hydrogen and hydrogen-like ions (He+, Li²+). Fails for multi-electron atoms.
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.