Problem 1
A photon of green light has a wavelength of nm. Find the photon's frequency, magnitude of momentum, and energy. Express the energy in both joules and electron volts.
Problem 4a
A laser used to weld detached retinas emits light with a wavelength of nm in pulses that are ms in duration. The average power during each pulse is W. How much energy is in each pulse in joules? In electron volts?
Problem 5a
A photon has momentum of magnitude kg-m/s. What is the energy of this photon? Give your answer in joules and in electron volts.
Problem 5b
A photon has momentum of magnitude kg-m/s. What is the wavelength of this photon? In what region of the electromagnetic spectrum does it lie?
Problem 6
The photoelectric threshold wavelength of a tungsten surface is nm. Calculate the maximum kinetic energy of the electrons ejected from this tungsten surface by ultraviolet radiation of frequency Hz. Express the answer in electron volts.
Problem 8
What would the minimum work function for a metal have to be for visible light (– nm) to eject photoelectrons?
Problem 10a
The photoelectric work function of potassium is eV. If light that has a wavelength of nm falls on potassium, find the stopping potential in volts.
Problem 10b
The photoelectric work function of potassium is eV. If light that has a wavelength of nm falls on potassium, find the kinetic energy, in electron volts, of the most energetic electrons ejected.
Problem 12
The cathode-ray tubes that generated the picture in early color televisions were sources of x rays. If the acceleration voltage in a television tube is kV, what are the shortest-wavelength x rays produced by the television?
Problem 17
X rays with initial wavelength nm undergo Compton scattering. What is the longest wavelength found in the scattered x rays? At which scattering angle is this wavelength observed?
Problem 20
A photon scatters in the backward direction (°) from a free proton that is initially at rest. What must the wavelength of the incident photon be if it is to undergo a change in wavelength as a result of the scattering?
Problem 21
X rays with an initial wavelength of m undergo Compton scattering. For what scattering angle is the wavelength of the scattered x rays greater by than that of the incident x rays?
Problem 22a
An electron and a positron are moving toward each other and each has speed in the lab frame. What is the kinetic energy of each particle?
Problem 23
An ultrashort pulse has a duration of fs and produces light at a wavelength of nm. What are the momentum and momentum uncertainty of a single photon in the pulse?
Problem 24
A horizontal beam of laser light of wavelength nm passes through a narrow slit that has width mm. The intensity of the light is measured on a vertical screen that is m from the slit.
(a) What is the minimum uncertainty in the vertical component of the momentum of each photon in the beam after the photon has passed through the slit?
(b) Use the result of part (a) to estimate the width of the central diffraction maximum that is observed on the screen.
Ch 38: Photons: Light Waves Behaving as Particles