Fill-in-the-Blank

Paragraph A — Photoelectric Effect

In the photoelectric effect, electrons are emitted from a metal surface when incident light has frequency greater than or equal to the __________ frequency ν_{0}. The minimum energy required to free an electron from the metal surface is called the __________ (φ), given by φ = __________. The maximum kinetic energy of photoelectrons is given by Einstein's equation: KE_max = __________. The stopping potential $V_{0}$ is related to KE_max by: e $V_{0}$ = __________, so $V_{0}$ = __________. Crucially, stopping potential depends on __________ of the incident light, NOT on its __________. Higher intensity increases the __________ (photocurrent) but leaves $V_{0}$ unchanged.

Key: threshold | work function | hν_{0} | hν − φ | KE_max | (hν − φ)/e | frequency | intensity | number of photoelectrons

Paragraph B — Three Key Graphs

The graph of KE_max vs frequency ν is a __________ line with slope equal to __________ and x-intercept equal to __________. This slope is __________ for all metals (universal). The graph of stopping potential $V_{0}$ vs frequency ν is also a straight line with slope equal to __________ and the same x-intercept __________. In the graph of photocurrent I vs applied voltage V, different intensities produce different __________ currents but all cross zero current at the same __________ voltage, confirming $V_{0}$ is intensity-independent.

Key: straight | h (Planck's constant) | ν_{0} | the same | h/e | ν_{0} | saturation | stopping (− $V_{0}$ )

Paragraph C — de Broglie

Louis de Broglie proposed in 1924 that every moving particle has an associated wavelength given by λ = __________. For a particle with kinetic energy KE, this becomes λ = __________. For an electron accelerated through potential V volts, a useful shortcut formula is λ = __________ (units: __________). This shortcut is valid ONLY for __________. The experimental confirmation of de Broglie's hypothesis came from the __________ experiment by Davisson and Germer in __________, where electrons showed __________ from a nickel crystal. For two particles at the same accelerating potential, the one with __________ mass has the longer wavelength, since λ ∝ __________.