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1. Energy Quantization and Wave-Particle Duality (a) Einstein provided an explanation for the observation of a wavelength threshold for the emission of electrons when a metal is illuminated by visible light. What concept did he invoke in his explanation? Concept = ________________________________________________________ (b) Atoms were found to emit and absorb light of only certain, discrete wavelengths. What concept did Bohr invoke to explain this observation? Concept = ________________________________________________________ (c) In the Franck-Hertz experiment, electrons of variable energy collide with lithium atoms. The first excitation threshold occurs at 1.85 eV. Compute the wavelength of light corresponding to this threshold. Wavelength = ______________________ m Part and max points (a) 4 (b) 4 (c) 5 Total (13) Your score
Page 3 of 10 2. Particles and Waves (a) An electron has a de Broglie wavelength of 2.00 ×10–9m. What is its velocity and energy? (b) The uncertainty of the position of a proton is 1.00 Å = 1.00 ×10–10m. What would be the uncertainty in its momentum p? (c) What is the longest de Broglie wavelength for a particle confined to a circle of radius R? Wavelength = ____________________________ Part and max points (a) 5 (b) 5 (c) 5 Total (15) Your score