Chapter 27 Quantum Physics CHAPTER 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 and when bombarded with photons of wavelength 1 emits photoelectrons with maximum energy KE1 Surface 2 has work function 2 and when bombarded by photons of wavelength 2 emits photoelectrons with maximum energy KE 2 If 1 2 then which of the following must be true a b c d KE1 KE 2 1 2 c for surface 1 is greater than c for surface 2 c for surface 2 is greater than c for surface 1 C3 The Compton wavelength h mec equals 0 002 43 nm In Compton scattering what is the greatest shift in wavelength that can occur a 2 h mec b 2 h mec c h mec d h mec C4 If a 1H nucleus a 2H nucleus and a 3H nucleus all had the same momentum which one has the greatest de Broglie wavelength a 1H b 2H c 3H 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 205 Chapter 27 Quantum Physics c i the electron ii the electron d i the proton ii the proton 27 1 Blackbody Radiation and Planck s Hypothesis 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 1017 Hz b 4 8 1017 Hz c 6 3 1017 Hz d 7 3 1017 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 00 108 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 3 206 Chapter 27 Quantum Physics b 1 c 3 d 9 207 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 m 1 nm 10 9 m 10 3 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 a as thermal radiation in the infrared region b at the wavelength given by Wien s displacement law c as ultraviolet light d a blackbody should not radiate 8 The ultraviolet catastrophe predicts that a all objects should radiate extreme amounts of ultraviolet light b as an object gets hotter its light will change from dull red to blue white c a black body can absorb an infinite amount of radiation if the radiation is in the ultraviolet region d the radiated energy approaches zero as the wavelength approaches zero 9 Star A has the peak of its blackbody radiation at A Star B has its peak at B which is onefourth that of A If Star A s surface temperature is TA how does the surface temperature TB of Star B compare a TB 16 TA b TB 4 TA c TB TA 4 d TB TA 16 10 If a blackbody is at 2000 C what will be the peak wavelength emitted a 1 67 m b 1 45 m c 1 27 m d 580 nm 208 Chapter 27 Quantum Physics 27 2 The Photoelectric Effect and the Particle Theory of Light 11 Blue light will not eject electrons from a certain metal however which one of the following may possibly eject electrons from that metal a infrared b ultraviolet c red d green 12 Light of wavelength 6 5 10 7 m has an energy of h 6 63 10 34 J s c 3 00 108 m s a 3 1 10 19 J b 3 3 10 19 J c 1 5 10 19 J d 1 7 10 19 J 13 If a monochromatic light beam with quantum energy value of 3 0 eV incident upon a photocell where the work function of the target metal is 1 60 eV what is the maximum kinetic energy of ejected electrons a 4 6 eV b 4 8 eV c 1 4 eV d 2 4 eV 14 Which of the following devices represent s a practical application of the photoelectric effect a hologram b photocell c both of the above choices d none of the above choices 15 According to Einstein what is true of the stopping potential for a photoelectric current as the wavelength of incident light becomes shorter a increases b decreases c remains constant d stopping potential is directly proportional to wavelength 209 Chapter 27 Quantum Physics 16 According to Einstein as the wavelength of the incident monochromatic light beam becomes shorter the work function of a target material in a phototube a increases b decreases c remains constant d is directly proportional to wavelength 17 What is the frequency of monochromatic light where the photon energy is 5 5 10 19 J h 6 63 10 34 J s a 2 2 1014 Hz b 4 4 1014 Hz c 8 3 1014 Hz d 9 8 1014 Hz 18 What is the wavelength of a monochromatic light beam where the photon energy is 5 00 10 19 J h 6 63 10 34 J s c 3 00 108 m s and 1 nm 10 9 m a 354 nm b 398 nm c 414 nm d 787 nm 19 What is the wavelength of a monochromatic light beam where the photon energy is 3 00 eV h 6 63 10 34 J s c 3 00 108 m s 1 nm 10 9 m and 1 eV 1 6 10 19 J a 311 nm b 414 nm c 622 nm d 1 243 nm 20 A monochromatic light beam is incident on a barium target which has a work function of 2 50 eV If a …