Question 1

In a photoelectric effect experiment at a frequency above cut off, the stopping potential is proportional to:

Accepted Answer

A)  the energy of the least energetic electron before it is ejected 
B)  the energy of the least energetic electron after it is ejected 
C)  the energy of the most energetic electron before it is ejected 
D)  the energy of the most energetic electron after it is ejected 
E)  the electron potential energy at the surface of the sample 
A)  the energy of the least energetic electron before it is ejected 
B)  the energy of the least energetic electron after it is ejected 
C)  the energy of the most energetic electron before it is ejected 
D)  the energy of the most energetic electron after it is ejected 
E)  the electron potential energy at the surface of the sample

Question 2

The surface of the Sun is at a temperature of approximately 5800 K, and radiates a peak wavelength of 500 nm. According to the Planck radiation law, what is its emitted intensity per unit wavelength at the peak?

Accepted Answer

A)  8.4 W/cm2∙nm 
B)  42 W/cm2∙nm 
C)  84 W/cm2∙nm 
D)  8.4 x 103 W/cm2∙nm 
E)  4.2 x 107 W/cm2∙nm 
A)  8.4 W/cm2∙nm 
B)  42 W/cm2∙nm 
C)  84 W/cm2∙nm 
D)  8.4 x 103 W/cm2∙nm 
E)  4.2 x 107 W/cm2∙nm

Question 3

The intensity of a light beam with a wavelength of 500 nm is 2000 W/m2. The photon flux is about:

Accepted Answer

A)  5* 1017 /m2.s 
B)  5 *1019 /m2.s 
C)  5 * 1021 /m2.s 
D)  5 * 1023 /m2.s 
E)  5 *1025 /m2.s 
A)  5* 1017 /m2.s 
B)  5 *1019 /m2.s 
C)  5 * 1021 /m2.s 
D)  5 * 1023 /m2.s 
E)  5 *1025 /m2.s

Question 4

The main problem that physicists had in understanding blackbody radiation before Planck's work was:

Accepted Answer

A)  Blackbody radiation came from objects that were not actually black. 
B)  The classically predicted frequency spectrum showed an infinitely large peak at low frequencies. 
C)  The classically predicted frequency spectrum showed an infinitely large peak at high frequencies. 
D)  The classically predicted frequency spectrum had a minimum intensity rather than a maximum as observed. 
E)  The classically predicted frequency spectrum had a maximum intensity that decreased with temperature, rather than increasing as observed. 
A)  Blackbody radiation came from objects that were not actually black. 
B)  The classically predicted frequency spectrum showed an infinitely large peak at low frequencies. 
C)  The classically predicted frequency spectrum showed an infinitely large peak at high frequencies. 
D)  The classically predicted frequency spectrum had a minimum intensity rather than a maximum as observed. 
E)  The classically predicted frequency spectrum had a maximum intensity that decreased with temperature, rather than increasing as observed.

Question 5

A free electron and a free proton have the same speed. This means that, compared to the matter wave associated with the proton, the matter wave associated with the electron has:

Accepted Answer

A)  a shorter wavelength and a greater frequency 
B)  a longer wavelength and a greater frequency 
C)  a shorter wavelength and a smaller frequency 
D)  the same wavelength and a greater frequency 
E)  a longer wavelength and a smaller frequency 
A)  a shorter wavelength and a greater frequency 
B)  a longer wavelength and a greater frequency 
C)  a shorter wavelength and a smaller frequency 
D)  the same wavelength and a greater frequency 
E)  a longer wavelength and a smaller frequency

Question 6

Electromagnetic radiation with a wavelength of 3.5 * 10-12 m is scattered from stationary electrons, and photons that have been scattered through 50 $\degree$ are detected. After a scattering event the magnitude of the photon's momentum is:

Accepted Answer

A)  0 kg.m/s 
B)  8.7 *10-23 kg.m/s 
C)  1.5 * 10-22 kg.m/s 
D)  2.0 *10-22 kg.m/s 
E)  2.2 * 10-22 kg.m/s 
A)  0 kg.m/s 
B)  8.7 *10-23 kg.m/s 
C)  1.5 * 10-22 kg.m/s 
D)  2.0 *10-22 kg.m/s 
E)  2.2 * 10-22 kg.m/s

Question 7

The work function for a certain sample is 2.3 eV. The stopping potential for electrons ejected from the sample by 7.0 * 1014-Hz electromagnetic radiation is:

Accepted Answer

A)  0 V 
B)  0.60 V 
C)  2.3 V 
D)  2.9 V 
E)  5.2 V 
A)  0 V 
B)  0.60 V 
C)  2.3 V 
D)  2.9 V 
E)  5.2 V

Question 8

Maxwell's equations are to electric and magnetic fields as __________ equation is to the wave function of the particle.

Accepted Answer

A)  Einstein's 
B)  Fermi's 
C)  Newton's 
D)  Schrödinger's 
E)  Bohr's 
A)  Einstein's 
B)  Fermi's 
C)  Newton's 
D)  Schrödinger's 
E)  Bohr's

Question 9

An electron with energy E is incident upon a potential energy barrier of height Epot < E and thickness L. If the reflection coefficient R = 0.05,

Accepted Answer

A)  the electron has a 0.05% chance of being reflected 
B)  the electron has a 5% chance of being reflected 
C)  the electron has a 95% chance of being reflected 
D)  the electron will be partially reflected and partially transmitted 
E)  the electron has no chance of being reflected 
A)  the electron has a 0.05% chance of being reflected 
B)  the electron has a 5% chance of being reflected 
C)  the electron has a 95% chance of being reflected 
D)  the electron will be partially reflected and partially transmitted 
E)  the electron has no chance of being reflected

Question 10

Consider the following: I. A photoelectric process in which all emitted electrons have energy less than hf, where f is the frequency of the incident light.
II) A photoelectric process in which some emitted electrons have kinetic energy greater than hf.
III) Compton scattering from stationary electrons for which the emitted light has a frequency that is greater than that of the incident light.
IV) Compton scattering from stationary electrons for which the emitted light has a frequency that is less than that of the incident light.
The only possible processes are:

Accepted Answer

A)  I 
B)  III 
C)  I and III 
D)  I and IV 
E)  II and IV 
A)  I 
B)  III 
C)  I and III 
D)  I and IV 
E)  II and IV

Question 11

In a photoelectric effect experiment the stopping potential is:

Accepted Answer

A)  the energy required to remove an electron from the sample 
B)  the kinetic energy of the most energetic electron ejected 
C)  the potential energy of the most energetic electron ejected 
D)  the photon energy 
E)  the electric potential that causes the electron current to vanish 
A)  the energy required to remove an electron from the sample 
B)  the kinetic energy of the most energetic electron ejected 
C)  the potential energy of the most energetic electron ejected 
D)  the photon energy 
E)  the electric potential that causes the electron current to vanish

Question 12

Identical particles, each with energy E, are incident on the following four potential energy barriers:   Rank the barriers in terms of the probability that the particles tunnel through them, from least probability to greatest probability.

Accepted Answer

A)  1, 2, 3, 4 
B)  4, 3, 2, 1 
C)  1 and 2 tied, then 3, then4 
D)  1, then 2 and 3 tied, then 4 
E)  3, 2, 1, 4 
A)  1, 2, 3, 4 
B)  4, 3, 2, 1 
C)  1 and 2 tied, then 3, then4 
D)  1, then 2 and 3 tied, then 4 
E)  3, 2, 1, 4

Question 13

Of the following, Compton scattering from electrons is most easily observed for:

Accepted Answer

A)  microwaves 
B)  infrared light 
C)  visible light 
D)  ultraviolet light 
E)  x rays 
A)  microwaves 
B)  infrared light 
C)  visible light 
D)  ultraviolet light 
E)  x rays

Question 14

What is the temperature of a burner on an electric stove when its glow is barely visible, at a wavelength of 700 nm? Assume the burner radiates as an ideal blackbody and that 700 nm represents the peak of its emission spectrum.

Accepted Answer

A)  41 K 
B)  240 K 
C)  410 K 
D)  2400 K 
E)  4100 K 
A)  41 K 
B)  240 K 
C)  410 K 
D)  2400 K 
E)  4100 K

Question 15

The significance of $\mid$$\Psi$$\mid$2 is:

Accepted Answer

A)  probability 
B)  energy 
C)  probability density 
D)  energy density 
E)  wavelength 
A)  probability 
B)  energy 
C)  probability density 
D)  energy density 
E)  wavelength

Question 16

The quantization of energy, E = nhf, is not important for an ordinary pendulum because:

Accepted Answer

A)  the formula applies only to mass-spring oscillators 
B)  the allowed energy levels are too closely spaced 
C)  the allowed energy levels are too widely spaced 
D)  the formula applies only to atoms 
E)  the value of h for a pendulum is too large 
A)  the formula applies only to mass-spring oscillators 
B)  the allowed energy levels are too closely spaced 
C)  the allowed energy levels are too widely spaced 
D)  the formula applies only to atoms 
E)  the value of h for a pendulum is too large

Question 17

A free electron has a momentum of 5.0 * 10-24 kg . m/s. Its wavelength, as given by its wave function, is:

Accepted Answer

A)  1.3 * 10-8 m 
B)  1.3 * 10-10 m 
C)  2.3 * 10-11 m 
D)  2.3 *10-13 m 
E)  none of these 
A)  1.3 * 10-8 m 
B)  1.3 * 10-10 m 
C)  2.3 * 10-11 m 
D)  2.3 *10-13 m 
E)  none of these

Exam 38: Photons and Matter Waves

In a photoelectric effect experiment at a frequency above cut off, the stopping potential is proportional to:

The surface of the Sun is at a temperature of approximately 5800 K, and radiates a peak wavelength of 500 nm. According to the Planck radiation law, what is its emitted intensity per unit wavelength at the peak?

The intensity of a light beam with a wavelength of 500 nm is 2000 W/m2. The photon flux is about:

The main problem that physicists had in understanding blackbody radiation before Planck's work was:

A free electron and a free proton have the same speed. This means that, compared to the matter wave associated with the proton, the matter wave associated with the electron has:

Electromagnetic radiation with a wavelength of 3.5 * 10-12 m is scattered from stationary electrons, and photons that have been scattered through 50 °\degree° are detected. After a scattering event the magnitude of the photon's momentum is:

The work function for a certain sample is 2.3 eV. The stopping potential for electrons ejected from the sample by 7.0 * 1014-Hz electromagnetic radiation is:

Maxwell's equations are to electric and magnetic fields as __________ equation is to the wave function of the particle.

An electron with energy E is incident upon a potential energy barrier of height Epot < E and thickness L. If the reflection coefficient R = 0.05,

In a photoelectric effect experiment the stopping potential is:

Identical particles, each with energy E, are incident on the following four potential energy barriers: Rank the barriers in terms of the probability that the particles tunnel through them, from least probability to greatest probability.

Of the following, Compton scattering from electrons is most easily observed for:

What is the temperature of a burner on an electric stove when its glow is barely visible, at a wavelength of 700 nm? Assume the burner radiates as an ideal blackbody and that 700 nm represents the peak of its emission spectrum.

The significance of ∣\mid∣Ψ\PsiΨ∣\mid∣ 2 is:

The quantization of energy, E = nhf, is not important for an ordinary pendulum because:

A free electron has a momentum of 5.0 * 10-24 kg . m/s. Its wavelength, as given by its wave function, is:

Measurement

Motion Along a Straight Line

Vector

Motion in Two and Three Dimensions

Force and Motion I

Force and Motion II

Kinetic Energy and Work

Potential Energy and Conservation of Energy

Center of Mass and Linear Momentum

Rotation

Rolling, Torque, and Angular Momentum

Equilibrium and Elasticity

Gravitation

Fluids

Oscillations

Waves I

Waves II

Temperature, Heat, and the First Law of Thermodynamics

The Kinetic Theory of Gases

Entropy and the Second Law of Thermodynamics

Electric Charge

Electric Fields

Gauss Law

Electric Potential

Capacitance

Current and Resistance

Circuits

Magnetic Fields

Magnetic Fields Due to Currents

Induction and Inductance

Electromagnetic Oscillations and Alternating Current

Maxwells Equations; Magnetism of Matter

Electromagnetic Waves

Images

Interference

Diffraction

Relativity

More About Matter Waves

All About Atoms

Conduction of Electricity in Solids

Nuclear Physics

Energy From the Nucleus

Quarks, Leptons, and the Big Bang

Filters

The intensity of a light beam with a wavelength of 500 nm is 2000 W/m². The photon flux is about:

Electromagnetic radiation with a wavelength of 3.5 * 10^-12 m is scattered from stationary electrons, and photons that have been scattered through 50 $\degree$ are detected. After a scattering event the magnitude of the photon's momentum is:

The work function for a certain sample is 2.3 eV. The stopping potential for electrons ejected from the sample by 7.0 * 10¹⁴-Hz electromagnetic radiation is:

An electron with energy E is incident upon a potential energy barrier of height E_pot < E and thickness L. If the reflection coefficient R = 0.05,

The significance of $\mid$ $\Psi$ $\mid$ ² is:

A free electron has a momentum of 5.0 * 10^-24kg . m/s. Its wavelength, as given by its wave function, is: