TB_chapter27

# TB_chapter27 - Chapter 27, Quantum Physics CHAPTER 27...

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Chapter 27, Quantum Physics C HAPTER 27 Conceptual Questions C1. Of photons of red, yellow, light, and blue light, which photons have the greatest energy? a. red b. yellow c. green d. blue C2. Surface #1 has work function 1 φ , and when bombarded with photons of wavelength 1 λ emits photoelectrons with maximum energy 1 KE . Surface #2 has work function 2 , and when bombarded by photons of wavelength 2 emits photoelectrons with maximum energy 2 KE . If 2 1 , then which of the following must be true? a. 2 1 KE KE b. 2 1 c. c for surface #1 is greater than c for surface #2. d. c for surface #2 is greater than c for surface #1. C3. The Compton wavelength, h/m e c , equals 0.002 43 nm. In Compton scattering, what is the greatest shift, Δ λ , in wavelength that can occur? a. Δ > 2 h/m λ e c b. Δ = 2 h/m λ e c c. Δ = h/m λ e c d. Δ λ < h/m e c C4. If a 1 H nucleus, a 2 H nucleus, and a 3 H nucleus all had the same momentum, which one has the greatest de Broglie wavelength? a. 1 H b. 2 H c. 3 H d. All three have the same de Broglie wavelength. C5. A proton and an electron each have the same de Broglie wavelength. (i) Which has the greater speed, and (ii) which has the greater kinetic energy? a. (i) the electron, (ii) Either one can have the greater kinetic energy. b. (i) the proton, (ii) Either one can have the greater kinetic energy. c. (i) the electron, (ii) the electron d. (i) the proton, (ii) the proton 27.1 Blackbody Radiation and Planck’s Hypothesis 205

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Chapter 27, Quantum Physics 1. Planck’s quantum theory is compatible with the experimental data related to which of the following? a. blackbody radiation b. the photoelectric effect c. line spectra emitted by hydrogen gas d. all of the above 2. As the temperature of a radiation emitting blackbody becomes higher, what happens to the peak wavelength of the radiation? a. increases b. decreases c. remains constant d. is directly proportional to temperature 3. A quantum of radiation has an energy of 2.0 keV. What is its frequency? ( h = 6.63 × 10 - 34 J s and 1 eV = 1.60 × 10 - 19 J) a. 3.2 × 10 17 Hz b. 4.8 × 10 17 Hz c. 6.3 × 10 17 Hz d. 7.3 × 10 17 Hz 4. If a quantum of radiation has an energy of 2.0 keV, what is its wavelength? ( h = 6.63 × 10 - 34 J s, 1 eV = 1.60 × 10 - 19 J, c = 3.00 × 10 8 m/s, and 1 nm = 10 - 9 m) a. 0.32 nm b. 0.41 nm c. 0.62 nm d. 1.02 nm 5. According to Wien’s displacement law, if the absolute temperature of a radiating blackbody is tripled, then the peak wavelength emitted will change by what factor? a. 1/3 b. 1 c. 3 d. 9 206
Chapter 27, Quantum Physics 6. What is the surface temperature of a distant star (which emits light as if it were a blackbody) where the peak wavelength is 480 nm? (Hint: The surface of the human body at 35 ° C has a peak wavelength of 941 μ m). (1 nm = 10 - 9 m = 10 -3 μ m) a. 4 510 K b. 5 100 K c. 6 040 K d. 6 350 K 7. Classical theories predict that most of the energy from a blackbody should be radiated:

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## This note was uploaded on 01/06/2012 for the course PHYS 201 taught by Professor Coffin during the Spring '09 term at Oregon State.

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TB_chapter27 - Chapter 27, Quantum Physics CHAPTER 27...

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