EXERCISES

Light of wavelength $488\hspace{0.17em}\mathrm{nm}$ is produced by an argon laser which is used in the photoelectric effect. When light from this spectral line is incident on the emitter, the stopping (cut-off) potential of photoelectrons is $0.38\hspace{0.17em}\mathrm{V}$. Find the work function of the material from which the emitter is made.

What is the

(a) momentum,

(b) speed, and

(c) de Broglie wavelength of an electron with kinetic energy of $120 \mathrm{eV}$.

What is the de Broglie wavelength of a ball of mass $0.060 \mathrm{Kg}$ moving at a speed of $1.0 \mathrm{m}/\mathrm{s}$?

An electron and a photon each have a wavelength of $1.0 \mathrm{nm}$. Find the kinetic energy of electron. Mass of electron, $m = 9.1\times {10}^{-31} \mathrm{J}$

For what kinetic energy of a neutron will the associated de Broglie wavelength be $1.40\times {10}^{-10} \mathrm{m}$?

Find the de Broglie wavelength of a neutron, in thermal equilibrium with matter, having an average kinetic energy of $(\raisebox{1ex}{$3$}\!\left/ \!\raisebox{-1ex}{$2)$}\right. \mathrm{kT}$ at $300 \mathrm{K}$. (Mass of neutron is $1.66\times {10}^{-27} \mathrm{Kg}$, Boltzman's constant is $1.38\times {10}^{-23} \mathrm{J}/\mathrm{k}$ and Plank's constant is $6.626\times {10}^{-34} \mathrm{Js}$)

Show that the wavelength of electromagnetic radiation is equal to the de Broglie wavelength of its quantum (photon).

What is the de Broglie wavelength of a nitrogen molecule in air at $300 \mathrm{K}$? Assume that the molecule is moving with the root-mean-square speed of molecules at this temperature. (Atomic mass of nitrogen $=14.0076 \mathrm{u}$)