Chapter 29: Introduction to Quantum Physics

Question: What is the maximum velocity of electrons ejected from a material by $80\mathrm{n}\mathrm{m}$ photons, if they are bound to the material by $4.73\mathrm{e}\mathrm{V}$?

Your pupils dilate when visible light intensity is reduced. Does wearing sunglasses that lack UV blockers increase or decrease the UV hazard to your eyes? Explain.

Photoelectrons from a material with a binding energy of $2.71\mathrm{e}\mathrm{V}$ are ejected by $420-\mathrm{n}\mathrm{m}$ photons. Once ejected, how long does it take these electrons to travel $2.50\mathrm{c}\mathrm{m}$ to a detection device?

Question: Photoelectrons from a material with a binding energy of $2.71\mathrm{e}\mathrm{V}$ are ejected by $420-\mathrm{n}\mathrm{m}$ photons. Once ejected, how long does it take these electrons to travel $2.50\mathrm{c}\mathrm{m}$ to a detection device?

A laser with a power output of $2.00\mathrm{m}\mathrm{W}$at a wavelength of $400\mathrm{n}\mathrm{m}$ is projected onto calcium metal. (a) How many electrons per second are ejected? (b) What power is carried away by the electrons, given that the binding energy is $2.71\mathrm{e}\mathrm{V}$?

Question: A laser with a power output of $2.00\mathrm{m}\mathrm{W}$ at a wavelength of $400\mathrm{n}\mathrm{m}$ is projected onto calcium metal. (a) How many electrons per second are ejected? (b) What power is carried away by the electrons, given that the binding energy is $2.71\mathrm{e}\mathrm{V}$?

Can a single microwave photon cause cell damage? Explain.

(a) Calculate the number of photoelectrons per second ejected from a $1.00\mathrm{m}{\mathrm{m}}^2$ area of sodium metal by $500\mathrm{n}\mathrm{m}\mathrm{E}\mathrm{M}$ radiation having an intensity of $1.30\mathrm{k}\mathrm{W}/{\mathrm{m}}^2$ (the intensity of sunlight above the Earth’s atmosphere). (b) Given that the binding energy is$2.28\mathrm{e}\mathrm{V}$, what power is carried away by the electrons? (c) The electrons carry away less power than brought in by the photons. Where does the other power go? How can it be recovered?

Red light having a wavelength of $700\mathrm{n}\mathrm{m}$ is projected onto magnesium metal to which electrons are bound by$3.68\mathrm{e}\mathrm{V}$. (a) Use $\mathrm{K}\mathrm{E}\mathrm{e}=\mathrm{h}\mathrm{f}--\mathrm{B}\mathrm{E}$ to calculate the kinetic energy of the ejected electrons. (b) What is unreasonable about this result? (c) Which assumptions are unreasonable or inconsistent?

Question: Red light having a wavelength of $700\mathrm{n}\mathrm{m}$ is projected onto magnesium metal to which electrons are bound by $3.68\mathrm{e}\mathrm{V}$. (a) Use $\mathrm{K}\mathrm{E}\mathrm{e}=\mathrm{h}\mathrm{f}--\mathrm{B}\mathrm{E}$ to calculate the kinetic energy of the ejected electrons. (b) What is unreasonable about this result? (c) Which assumptions are unreasonable or inconsistent?