複選題Problem 15 Which of the following statements are correct? (A) For a collection of hydrogen atoms in the ground state illuminated by ultraviolet light of wavelength 59.0 nm, the kinetic energy of the emitted electrons is 21.0 eV, neglecting a small recoil kinetic energy imparted to the proton. (B) For protons incident on a copper foil 5-µm thick, the proton kinetic energy required to achieve a distance of closest approach of 5.0 fm is about 8.4 meV. (C) The velocity of electron in the n = 3 state of hydrogen is 730 km/s. (D) The shortest wavelength of the Lyman series of singly ionized helium is 22.8 nm. (E) According to Bohr's correspondence principle, the quantum distributions approach the classical distribution when n is large.

Problem 6 Consider the transmission of an incident electron with energy E through the one dimensional step potential barrier V(x) with V(x ＜ 0) = 0 outside the barrier, and V(x ＞ 0) = Vo in the barrier (V0 ＞ 0). Which of the following statements is CORRECT about the transmission coefficient T? (A) If the incident electron comes from x = +infinity, with E＞ V0,then the corresponding T = 1. (B) If the incident electron comes from x = - infinity, with E ＞V0, then the corresponding T = 1. (C) If the incident electron comes from x = - infinity, with E＜V0, then it has a nonvanishing probability in the barrier as well as T ＞ 0 due to quantum tunneling. (D) Replace V(x) by a potential barrier of finite width, with V(0 ＜ x ＜W) = Vo in the barrier and V(x) = 0 outside the barrier. An incident electron with E＜V0 has T ＞ 0 due to quantum tunneling. (E) None of the above.

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