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quantum physics
1. *Chapter 38, Problem 11 GO
A sodium lamp emits light at the power P = 110 W and at the wavelength λ = 567 nm, and the emission is uniform
in all directions. (a) What is the rate of photon emission? (b) What is the rate per square meter at which photons
are intercepted by a screen at a distance of 1.40 m from the lamp?
(a) Number
3.137639601570E+20
Units s^-1
(b) Number
1.273905235282E+19
Units 1/(s*m^2)
Answer a1: significant digits are disabled; the tolerance is +/-2%
Answer b1: significant digits are disabled; the tolerance is +/-2%
2. *Chapter 38, Problem 19 GO
The stopping potential for electrons emitted from a surface illuminated by light of wavelength 517 nm is 0.610 V.
When the incident wavelength is changed to a new value, the stopping potential is 1.42 V. (a) What is this new
wavelength? (b) What is the work function for the surface?
(a) Number
386.479138156586
(b) Number
1.790046363709
Units nm
Units eV
Answer a1: significant digits are disabled; the tolerance is +/-2%
Answer b1: significant digits are disabled; the tolerance is +/-2%
3. *Chapter 38, Problem 30
X rays of wavelength 0.0178 nm are directed in the positive direction of an x axis onto a target containing loosely
bound electrons. For Compton scattering from one of those electrons, at an angle of 157°, what are (a) the Compton
shift (in pm), (b) the corresponding change in photon energy (in keV), (c) the kinetic energy (in keV) of the
recoiling electron, and (d) the angle between the positive direction of the x axis and the electron's direction of
motion? The electron Compton wavelength is 2.43 x 10-12 m.
(a) Number
4.659720925932
Units pm
(b) Number
-14.452974435381
(c) Number
14.452974435381
Units keV
(d) Number
10.151055353163
Units ° (degrees)
Answer
Answer
Answer
Answer
Units keV
a1: significant digits are disabled; the tolerance is +/-2%
b1: significant digits are disabled; the tolerance is +/-2%
c1: significant digits are disabled; the tolerance is +/-2%
d1: significant digits are disabled; the tolerance is +/-2%
4. *Chapter 38, Problem 36 GO
What is the maximum kinetic energy of electrons (in keV) knocked out of a thin copper foil by Compton scattering of
an incident beam of 18.3 keV X rays? Assume the work function is negligible. The electron Compton wavelength is
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2.43 x 10-12 m.
Number
1.221500950999
Units keV
Significant digits are disabled; the tolerance is +/-2%
5. *Chapter 38, Problem 47
Singly charged sodium atoms are accelerated through a potential difference of 365 V. (a) What is the momentum
acquired by such an ion? (b) What is its de Broglie wavelength (in pm)? The mass of a sodium ion is 3.819 x 10-26
kg.
(a) Number
2.113330958463E-21
(b) Number
0.313533475363
Units kg·m/s or N·s
Units pm
Answer a1: significant digits are disabled; the tolerance is +/-2%
Answer b1: significant digits are disabled; the tolerance is +/-2%
6. *Chapter 38, Problem 63
The uncertainty in the position of an electron along an x axis is given as 56 pm. What is the least uncertainty in any
simultaneous measurement of the momentum component px of this electron?
Number
1.883144023084E-24
Units kg·m/s or N·s
Significant digits are disabled; the tolerance is +/-2%
7. *Chapter 38, Problem 66 GO
Suppose a beam of 4.70 eV protons strikes a potential energy barrier of height 6.00 eV and thickness 0.620 nm, at a
rate equivalent to a current of 1150 A. How many years would you have to wait (on average) for one proton to be
transmitted through the barrier?
Number
2.703868235564E+105
Units years
Significant digits are disabled; the tolerance is +/-2%
8. Simulation: Photoelectric Effect, Question 1
In this simulation of a photoelectric effect experiment, light of a particular frequency shines on a metal plate. If the
energy of the photons is larger than the work function of the metal, electrons are ejected. By graphing the
maximum kinetic energy (KEmax ) of the electrons as a function of frequency you can determine Planck's constant,
and the work function of the metal.
The procedure in this virtual experiment goes like this:
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1. Choose the material to be used as the plate. Set the battery voltage to zero, and start at a low frequency. If the
current is zero, the frequency is below the threshold frequency required to eject electrons. Press the ''Plot data
point'' button to record the voltage (zero) at a few frequencies below the threshold frequency.
2. When you increase the frequency above the threshold, you will see a non-zero current reading. This means
electrons are being ejected from the metal. To determine their maximum kinetic energy (KEmax ), slowly increase
the battery voltage until the current returns to zero. Press the ''Plot data point'' button to record the maximum
kinetic energy of the ejected for this frequency of incident light.
3. Plot several points above the threshold frequency, increasing the frequency and finding the maximum kinetic
energy each time by finding the minimum battery voltage required to bring the current to zero.
4. When you are satisfied with your points, hit the ''Linear Fit'' button. See if you can determine the work function
of the metal and Planck's constant from the slope and intercept of the straight line plotted in the simulation. Note
that the value given for the slope in the simulation should actually be multiplied by 10-15 to be stated
correctly in units of eV s.
5. Pick a different material for the plate and repeat the process.
(a) How do you determine the work function, the threshold frequency, and Planck's constant from the straight line
plotted in the simulation? Select all the statements below that apply.
The slope of the line is the work function.
The slope of the line is the threshold frequency.
The slope of the line is Planck's constant.
The x-intercept is the work function.
The x-intercept is the threshold frequency.
The x-intercept is Planck's constant.
The y-intercept is the work function.
The y-intercept is the threshold frequency.
The y-intercept is Planck's constant.
The negative of the y-intercept is the work function.
The negative of the y-intercept is the threshold frequency.
The negative of the y-intercept is Planck's constant.
(b) Assuming you can carry out measurements with infinite precision, when you repeat the photoelectric
experiment for two or three different metals do you expect any of the parameters to be the same for the resulting
straight lines? Select all the statements below that apply.
All the lines should have the same slope.
All the lines should have the same x-intercept.
All the lines should have the same y-intercept.
None of the above.
9. Test Bank, Question 10
Rank following electromagnetic radiations according to the energies of their photons, from least to greatest.
1. blue light
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2. yellow light
3. x-rays
4. radio waves
3, 2, 1, 4
4, 1, 2, 3
1, 2, 3, 4
3, 1, 2, 4
4, 2, 1, 3
10. Test Bank, Question 20
In Compton scattering from stationary particles the maximum change in wavelength can be made smaller by
using:
higher frequency radiation
lower frequency radiation
more massive particles
less massive particles
particles with greater charge
11. Test Bank, Question 30
Evidence for the wave nature of matter is:
electron diffraction experiments of Davisson and Germer
Thompson's measurement of e/m
Young's double slit experiment
the Compton effect
Lenz's law
12. Test Bank, Question 40
A free electron and a free proton have the same kinetic energy. This means that, compared to the matter wave
associated with the proton, the matter wave associated with the electron has:
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a longer wavelength and a greater frequency
a shorter wavelength and a smaller frequency
a shorter wavelength and the same frequency
a shorter wavelength and a greater frequency
a longer wavelength and the same frequency
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