Question 1

What is the de Broglie wavelength of an electron traveling at 1×105 m s-1

Accepted Answer

A)   6.6×10-39 m
B)   6.6×10-30 m
C)   4.2×10-18 m
D)   7.3×10-9 m
E)   5.1×10-8 m D

Question 2

In the photoelectric effect, increasing the intensity of the light will

Accepted Answer

A)   ensure that electrons will be emitted from all metals.
B)   cause more electrons to be emitted from the metal if the frequency is sufficiently high.
C)   cause the electrons to be emitted with higher kinetic energy if the frequency is sufficiently high.
D)   have no effect on the experiment.
E)   both b and c B

Question 3

Calcium has a work function of 4.64×10-19 J. Which of the following wavelengths will eject electrons from calcium?

Accepted Answer

A)   375.2 nm
B)   401.8 nm
C)   442.4 nm
D)   a & b
E)   a, b, & c D

Question 4

Estimate the de Broglie wavelength for a golf ball traveling at 10 m s-1

Accepted Answer

A)   10-51 m
B)   10-35 m
C)   10-21 m
D)   10-6 m
E)   10 m

Question 5

The work function for aluminum is 6.53×10-19 J. If a surface of aluminum is irradiated with 400 nm what is the maximum kinetic energy of the electrons emitted from the surface due to the photo-electric effect?

Accepted Answer

A)   4.13×105 m s-1
B)   5.85×105 m s-1
C)   1.04×106 m s-1
D)   1.20×106 m s-1
E)   no electrons will be emitted

Question 6

According to Bohr's model of the atom, which is the largest radius?

Accepted Answer

A)   the n=1 state of H
B)   the n=2 state of H
C)   the n=3 state of Li2+
D)   the n=3 state of H
E)   the n=4 state of He+

Question 7

Femtosecond lasers can produce very short pulses of light. How long would it take a short pulse of light to travel across a 3 m table?

Accepted Answer

A)   10-15 s
B)   10-12 s
C)   10-8 s
D)   10-4 s
E)   10 s

Question 8

What is the frequency of x-ray radiation with a wavelength of 1 nm?

Accepted Answer

A)   1×10-9 s-1
B)   3×10-9 s-1
C)   1×109 s-1
D)   3×1015 s-1
E)   3×1017 s-1

Question 9

Electromagnetic radiation cannot typically pass through conductive metal mesh in which the holes are smaller than the wavelength of the radiation. Which is the largest mesh that would effectively block out radiation at 5 GHz?

Accepted Answer

A)   1 m
B)   10 cm
C)   1 mm
D)   100 mm
E)   10 nm

Question 10

What is the probability of finding a particle in a box of length L between zero and L/2?

Accepted Answer

A)   1
B)   0.5
C)   0.25
D)   L/2
E)   it depends on the quantum number n

Question 11

In the photoelectric effect, increasing the frequency of the light

Accepted Answer

A)   cause fewer electrons to be emitted from the metal if the frequency is sufficiently high.
B)   cause more electrons to be emitted from the metal if the frequency is sufficiently high.
C)   cause the electrons to be emitted with higher kinetic energy if the frequency is sufficiently high.
D)   have no effect on the experiment.
E)   both b and c

Question 12

Increasing the temperature of a black-body will cause

Accepted Answer

A)   the total intensity of emitted radiation to increase
B)   the peak of the emission spectrum to shift to longer wavelengths
C)   the peak of the emission spectrum to shift to shorter wavelengths
D)   both a & b
E)   both a & c

Question 13

Assuming they have the same force constant, the ratio the vibrational frequency for 16O2 to 18O2 is

Accepted Answer

A)   8 to 9
B)   9 to 8
C)   3 to Ö8
D)   Ö8 to 3
E)   they are the same

Question 14

Radiation from which region of the electromagnetic spectrum will induce molecular vibrations without inducing electronic transitions?

Accepted Answer

A)   ultraviolet
B)   X-rays
C)   microwave
D)   infrared
E)   γ -rays

Question 15

Proper wavefunctions ( ψ ) in quantum mechanics must be normalized. Which statement below best summarizes this mathematically?

Accepted Answer

A)    ∫−∞∞[ψ(x) ]2dx=1\int_{-\infty}^{\infty}[\psi(x) ]^{2} d x=1∫−∞∞​[ψ(x) ]2dx=1 
B)    ∫−∞∞ψ(x) dx=1\int_{-\infty}^{\infty} \psi(x)  d x=1∫−∞∞​ψ(x) dx=1 
C)    ∫−∞∞[ψ(x) ]2dx=0\int_{-\infty}^{\infty}[\psi(x) ]^{2} d x=0∫−∞∞​[ψ(x) ]2dx=0 
D)    lim⁡x→∞\lim _{x \rightarrow \infty}limx→∞​   ψ(x) =0\psi(x) =0ψ(x) =0 
E)    ψ(x) =sin⁡(nπxL) ;n=1,2,3…\psi(x) =\sin \left(\frac{n \pi x}{L}\right)  ; n=1,2,3 \ldotsψ(x) =sin(Lnπx​) ;n=1,2,3…

Question 16

The wave function for a n=5 state of the particle in a box has how many nodes?

Accepted Answer

A)   1
B)   3
C)   4
D)   5
E)   6

Question 17

The position of an electron in a Be2+ ion is known to 5.0×10-11 m. What is the uncertainty in its velocity?

Accepted Answer

A)   2.0×105 m s-1
B)   1.2×106 m s-1
C)   4.6×106 m s-1
D)   9.2×106 m s-1
E)   3.0×108 m s-1

Question 18

If the bond in carbon monoxide is modeled as a harmonic oscillator the force constant is 1860 N m-1, and the reduced mass is 6.86 amu. What is the energy of the ground vibrational state of CO?

Accepted Answer

A)   1.35×10-21 J
B)   2.71×10-21 J
C)   3.53×10-21 J
D)   2.13×10-20 J
E)   4.26×10-20 J

Question 19

Which has a shorter wavelength: an electron with a kinetic energy of 4×10-19 J or a photon with an energy of 4×10-19 J?

Accepted Answer

A)   the electron
B)   the photon
C)   they will have the same wavelength
D)   there is no way to know

Question 20

According to the Bohr model of the atom, which is highest in energy?

Accepted Answer

A)   n=1 electron in He+
B)   n=2 electron in H
C)   n=2 electron in He+
D)   n=3 electron in Li2+
E)   n=3 electron in H

Exam 4: Introduction to Quantum Mechanics

What is the de Broglie wavelength of an electron traveling at 1×10⁵ m s^-¹

In the photoelectric effect, increasing the intensity of the light will

Calcium has a work function of 4.64×10^-¹⁹ J. Which of the following wavelengths will eject electrons from calcium?

Estimate the de Broglie wavelength for a golf ball traveling at 10 m s^-¹

The work function for aluminum is 6.53×10^-¹⁹ J. If a surface of aluminum is irradiated with 400 nm what is the maximum kinetic energy of the electrons emitted from the surface due to the photo-electric effect?