Question 1

Consider a two-slit interference experiment like the one shown in figure Q3.7b. The distance between adjacent bright spots in the interference pattern on the screen ,
 
-The spacing between the slits increases.

Accepted Answer

A)  increases 
B)  decreases 
C)  remains the same

Question 2

Consider the experimental evidence we have discussed in the past few chapters. Classify the following experimental results according to the following scheme: For the quantons in question, the results:
-When light shines on a surface, at least a few electrons seem to get ejected virtually as soon as the surface is illuminated, even if the light is extremely dim.

Accepted Answer

The answer of Consider the experimental evidence we have discussed...

Question 3

Suppose that at time $t=0$ an electron in a magnetic field in the $+z$ direction has state $|\psi(0)\rangle=|+x\rangle$. Let $\omega=\left[E_{+}-E_{-}\right] / \hbar$.
-(a) The expectation value $\left\langle s_{z}\right\rangle$ as a function of time in this case is which of the below?

Accepted Answer

A)  $+\frac{1}{2} \hbar$ 
B)  $-\frac{1}{2} \hbar$ 
C)  0 
D)  $+\frac{1}{2} \hbar \cos \omega t$ 
E)  $+\frac{1}{2} \hbar \sin \omega t$
F) Something else (specify)

Question 4

A nucleus with binding energy $E_{b 1}$ fuses with one having binding energy $E_{b 2}$. The resulting nucleus has binding energy $E_{b 3}$. What is the total energy released in this fusion reaction?

Accepted Answer

A)  $E_{b 1}+E_{b 2}-E_{b 3}$ 
B)  $E_{b 3}-E_{b 1}-E_{b 2}$ 
C)  $E_{b 3}+E_{b 1}+E_{b 2}$ 
D)  $-E_{b 3}-E_{b 1}-E_{b 2}$ 
E)  One cannot answer without more information.

Question 5

The moderator in a fission reactor

Accepted Answer

A)  Slows down neutrons to make them more effective. 
B)  Absorbs neutrons to help control the chain reaction. 
C)  Scatters neutrons evenly throughout the fuel. 
D)  Keeps the chain reaction progressing slowly. 
E)  Has some other purpose (specify).

Question 6

In a spectrum chart (like the one shown in figure Q11.2), the emission lines produced by a quantum harmonic oscillator

Accepted Answer

A)  Get closer together (in energy) as we go to the right. 
B)  Are evenly spaced (in energy). 
C)  Get farther apart (in energy) as we go to the right.

Question 7

The main reason that gamma photons are more penetrating than either alpha particles or electrons is that

Accepted Answer

A)  They are uncharged. 
B)  They have no rest mass. 
C)  They travel at speed $c$. 
D)  They have more energy than electrons. 
E)  They don't ionize atoms as electrons do.

Question 8

The main reason that massive nuclei don't simply shed protons to relieve the instability caused by too much electrostatic repulsion is that

Accepted Answer

A)  Energy would not be conserved for typical values of $\boldsymbol{A}$.} 
B)  This would lead to openings in proton energy levels. 
C)  Protons aren't repelled as strongly as alpha particles. 
D)  Isolated protons can't exist outside an atom.

Question 9

Suppose we add a certain amount of energy to a simple quantum harmonic oscillator, increasing its energy from $E_{n}$ to $E_{n+1}$. Adding the same amount of energy again will increase its energy to $E_{n+2}$.

Accepted Answer

A) True 
 B)False

Question 10

In experiments involving the setup shown in figure Q4.1b, the value that the voltmeter displays increases for a short period of time after light starts shining on the cathode, but then quickly settles down to a fixed value. Why?

Accepted Answer

A)  The cathode eventually stops emitting electrons. 
B)  The kinetic energy of ejected electrons starts out small but quickly reaches a maximum value. 
C)  The charge difference between the cathode and anode is initially small but with time becomes so large that no electron from the cathode can make it to the anode. 
D)  The cathode eventually runs out of electrons to emit. 
E)  Some other explanation (describe).

Question 11

A charged particle moving in the magnetic field created by an external magnet experiences a force that is perpendicular to both the particle's velocity $\vec{v}$ and the direction of the magnetic field $\vec{B}$ in the sense indicated by your right thumb if your right index finger points in the direction of $\vec{v}$ and your adjacent finger points in the direction of $\vec{B}$. (The magnetic field $\vec{B}$, in turn, points away from the external magnet's north pole and toward its south pole.) A certain radioactive substance emits quantons that, when placed in a magnetic field directed away from the observer, bend to the right side of their direction of travel. These nuclei are decaying via which kind of process?

Accepted Answer

A)  An alpha decay process} 
B)  A beta decay process} 
C)  A gamma decay process 
D)  There is not enough information to specify.

Question 12

For experiments involving the setup shown in figure $\mathrm{Q} 4.1 \mathrm{~b}$, which of the following possible results (if seen) regarding the final value displayed by the voltmeter would probably not be consistent with the wave model of light?

(b) Metallic plate (cathode)

Accepted Answer

A)  It increases as the light's intensity increases. 
B)  It is independent of the light's intensity. 
C)  It varies as the light's wavelength changes. 
D)  It increases as the rate of electron ejection increases.

Question 13

A sinusoidal standing sound wave inside a tube that is open at both ends must fit between the tube's ends

Accepted Answer

A)  An integer number of wavelengths. 
B)  An integer number of half-wavelengths. 
C)  An integer number of quarter-wavelengths 
D)  An odd-integer number of half-wavelengths. 
E)  An odd-integer number of quarter-wavelengths.

Question 14

Consider an experiment where we send monochromatic light to a distant screen through a single narrow slit. The distance between adjacent dark fringes in the diffraction pattern displayed on the screen
-The intensity of the light increases.

Accepted Answer

A)  increases 
B)  decreases 
C)  remains the same

Question 15

Weak-interaction processes conserve both electric charge and a quantity called "lepton number." Electrons have lepton number $=+1$, positrons have lepton number -1 , and nucleons have lepton number $=0$. Study the weak interactions in this chapter.
-(a) What can you infer about the lepton number of the neutrino?

Accepted Answer

A)  This quanton has lepton number $=+1$. 
B)  This quanton has lepton number $=-1$. 
C)  This quanton has lepton number $=0$. 
D)  One cannot determine this quanton's lepton number from the processes we have studied.

Question 16

We can consider the state $|+x\rangle$ to be a superposition of $|+z\rangle$ and $|-z\rangle$ states.

Accepted Answer

A) True 
 B)False

Question 17

Imagine that an electron with an initial spin state
$$|\psi\rangle=\left[\begin{array}{c}
\frac{3}{5} \
-\frac{4}{5}
\end{array}\right]$$
Goes into an SGx device and comes out the - channel of that device. The electron's spin state is now

Accepted Answer

A)  $\left[\begin{array}{l}\sqrt{1 / 2} \ \sqrt{1} / 2\end{array}\right]$ 
B)  $\left[\begin{array}{l}-\sqrt{1 / 2} \ -\sqrt{1 / 2}\end{array}\right]$ 
C)  $\left[\begin{array}{l}\sqrt{1 / 2} \ -\sqrt{1 / 2}\end{array}\right]$ 
D)  $\left[\begin{array}{l}1 \ 0\end{array}\right]$ 
E)  $\left[\begin{array}{l}0 \ 1\end{array}\right]$

Question 18

A positron will travel roughly as far through a given material as an electron with the same energy.

Accepted Answer

A) True 
 B)False

Question 19

Must all physically reasonable wave functions be wavelike in classically allowed regions and exponential-like in forbidden regions (A), or does this apply only to solutions to the Schrödinger equation (B)?

Accepted Answer

A)  Forbidden regions 
B)  Does this apply only to solutions to the Schrödinger equation

Question 20

${ }_{92}^{235} \mathrm{U}$ (uranium) can decay to ${ }_{82}^{206} \mathrm{~Pb}$ (lead) through an appropriate sequence of alpha and beta decay processes.

Accepted Answer

A) True 
 B)False

Exam 5: Matter Behaves Like Waves Quantum Physics

Consider a two-slit interference experiment like the one shown in figure Q3.7b. The distance between adjacent bright spots in the interference pattern on the screen , -The spacing between the slits increases.

Suppose that at time $t=0$ an electron in a magnetic field in the $+z$ direction has state $|\psi(0) \rangle=|+x\rangle$ . Let $\omega=\left[E_{+}-E_{-}\right] / \hbar$ . -(a) The expectation value $\left\langle s_{z}\right\rangle$ as a function of time in this case is which of the below?

A nucleus with binding energy $E_{b 1}$ fuses with one having binding energy $E_{b 2}$ . The resulting nucleus has binding energy $E_{b 3}$ . What is the total energy released in this fusion reaction?

The moderator in a fission reactor

In a spectrum chart (like the one shown in figure Q11.2) , the emission lines produced by a quantum harmonic oscillator

The main reason that gamma photons are more penetrating than either alpha particles or electrons is that

The main reason that massive nuclei don't simply shed protons to relieve the instability caused by too much electrostatic repulsion is that

Suppose we add a certain amount of energy to a simple quantum harmonic oscillator, increasing its energy from $E_{n}$ to $E_{n+1}$ . Adding the same amount of energy again will increase its energy to $E_{n+2}$ .

In experiments involving the setup shown in figure Q4.1b, the value that the voltmeter displays increases for a short period of time after light starts shining on the cathode, but then quickly settles down to a fixed value. Why?

A sinusoidal standing sound wave inside a tube that is open at both ends must fit between the tube's ends

Consider an experiment where we send monochromatic light to a distant screen through a single narrow slit. The distance between adjacent dark fringes in the diffraction pattern displayed on the screen -The intensity of the light increases.

We can consider the state $|+x\rangle$ to be a superposition of $|+z\rangle$ and $|-z\rangle$ states.

Imagine that an electron with an initial spin state $|\psi\rangle=\left[\begin{array}{c}\frac{3}{5} \\-\frac{4}{5}\end{array}\right]$ Goes into an SGx device and comes out the - channel of that device. The electron's spin state is now

A positron will travel roughly as far through a given material as an electron with the same energy.

Must all physically reasonable wave functions be wavelike in classically allowed regions and exponential-like in forbidden regions (A) , or does this apply only to solutions to the Schrödinger equation (B) ?

${ }_{92}^{235} \mathrm{U}$ (uranium) can decay to ${ }_{82}^{206} \mathrm{~Pb}$ (lead) through an appropriate sequence of alpha and beta decay processes.

Exam 5: Matter Behaves Like Waves Quantum Physics

Consider a two-slit interference experiment like the one shown in figure Q3.7b. The distance between adjacent bright spots in the interference pattern on the screen , -The spacing between the slits increases.

A nucleus with binding energy Eb1E_{b 1}Eb1​ fuses with one having binding energy Eb2E_{b 2}Eb2​ . The resulting nucleus has binding energy Eb3E_{b 3}Eb3​ . What is the total energy released in this fusion reaction?

The moderator in a fission reactor

In a spectrum chart (like the one shown in figure Q11.2) , the emission lines produced by a quantum harmonic oscillator

The main reason that gamma photons are more penetrating than either alpha particles or electrons is that

The main reason that massive nuclei don't simply shed protons to relieve the instability caused by too much electrostatic repulsion is that

Suppose we add a certain amount of energy to a simple quantum harmonic oscillator, increasing its energy from EnE_{n}En​ to En+1E_{n+1}En+1​ . Adding the same amount of energy again will increase its energy to En+2E_{n+2}En+2​ .

In experiments involving the setup shown in figure Q4.1b, the value that the voltmeter displays increases for a short period of time after light starts shining on the cathode, but then quickly settles down to a fixed value. Why?

For experiments involving the setup shown in figure Q4.1 b\mathrm{Q} 4.1 \mathrm{~b}Q4.1 b , which of the following possible results (if seen) regarding the final value displayed by the voltmeter would probably not be consistent with the wave model of light? (b) Metallic plate (cathode)

A sinusoidal standing sound wave inside a tube that is open at both ends must fit between the tube's ends

Consider an experiment where we send monochromatic light to a distant screen through a single narrow slit. The distance between adjacent dark fringes in the diffraction pattern displayed on the screen -The intensity of the light increases.

We can consider the state ∣+x⟩|+x\rangle∣+x⟩ to be a superposition of ∣+z⟩|+z\rangle∣+z⟩ and ∣−z⟩|-z\rangle∣−z⟩ states.

Imagine that an electron with an initial spin state ∣ψ⟩=[35−45]|\psi\rangle=\left[\begin{array}{c}\frac{3}{5} \\-\frac{4}{5}\end{array}\right]∣ψ⟩=[53​−54​​] Goes into an SGx device and comes out the - channel of that device. The electron's spin state is now

A positron will travel roughly as far through a given material as an electron with the same energy.

Must all physically reasonable wave functions be wavelike in classically allowed regions and exponential-like in forbidden regions (A) , or does this apply only to solutions to the Schrödinger equation (B) ?

92235U{ }_{92}^{235} \mathrm{U}92235​U (uranium) can decay to 82206 Pb{ }_{82}^{206} \mathrm{~Pb}82206​ Pb (lead) through an appropriate sequence of alpha and beta decay processes.

A nucleus with binding energy $E_{b 1}$ fuses with one having binding energy $E_{b 2}$ . The resulting nucleus has binding energy $E_{b 3}$ . What is the total energy released in this fusion reaction?

Suppose we add a certain amount of energy to a simple quantum harmonic oscillator, increasing its energy from $E_{n}$ to $E_{n+1}$ . Adding the same amount of energy again will increase its energy to $E_{n+2}$ .

We can consider the state $|+x\rangle$ to be a superposition of $|+z\rangle$ and $|-z\rangle$ states.

Imagine that an electron with an initial spin state $|\psi\rangle=\left[\begin{array}{c}\frac{3}{5} \\-\frac{4}{5}\end{array}\right]$ Goes into an SGx device and comes out the - channel of that device. The electron's spin state is now

${ }_{92}^{235} \mathrm{U}$ (uranium) can decay to ${ }_{82}^{206} \mathrm{~Pb}$ (lead) through an appropriate sequence of alpha and beta decay processes.