4. A beam of ultraviolet light with wavelength $250\mathrm{nm}$ shines on a metal surface and ejects photoelectrons with a maximum speed of 0.004c. Which of the following statements is correct? Given that the light velocity $c = 3\times 10^{8}\mathrm{m / s}$, the Planck's constant $h = 6.626\times 10^{-34}\mathrm{J\cdot s}$, the elementary positive charge $q = 1.6\times 10^{-19}\mathrm{C}$, and the electron mass $m_{e} = 9.11\times 10^{-31}\mathrm{kg}$.
(A) The work function of the metal is $0.87\mathrm{eV}$.
(B) A wavelength larger than $1.45\mu \mathrm{m}$ can eject electrons from this metal.
(C) The photon energy is $4.10\mathrm{eV}$.
(D) The threshold frequency is about $1.2 \times 10^{15} \mathrm{~Hz}$.
(E) The kinetic energy of the photoelectron is $6.56 \times 10^{-19} \mathrm{eV}$.
統計: 尚無統計資料