Let's Review Regents: Physics—Physical Setting

Miriam A. Lazar

Chapter 13

Modern Physics - all with Video Answers

Educators

Chapter Questions

Problem 1

The ratio of the energy of a quantum of electromagnetic radiation to its frequency is
(A) the electrostatic constant
(B) the electron-volt
(C) the gravitational constant
(D) Planck's constant

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Problem 2

The energy of a photon varies directly with its
(A) frequency
(B) wavelength
(C) speed
(D) rest mass

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Problem 3

According to the quantum theory of light, the energy of light is carried in discrete units called
(A) alpha particles
(B) protons
(C) photons
(D) photoelectrons

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Problem 4

Which graph best represents the energy of a photon as a function of its frequency?

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Problem 5

Which graph best represents the relationship between the energy of a photon and its wavelength?

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Problem 6

Light demonstrates the characteristics of
(A) particles, only
(B) waves, only
(C) both particles and waves
(D) neither particles nor waves

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Problem 7

Which color of light has the greatest energy per photon?
(A) red
(B) green
(C) blue
(D) violet

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Problem 8

What is the energy of a photon of blue light whose frequency is 6 $\times 10^{14}$ hertz?
(A) $4 \times 10^{-6} \mathrm{~J}$
(B) $4 \times 10^{-10} \mathrm{~J}$
(C) $4 \times 10^{-14} \mathrm{~J}$
(D) $4 \times 10^{-19} \mathrm{~J}$

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Problem 9

The wavelength of photon $A$ is greater than that of photon $B$. Compared to the energy of photon $A$, the energy of photon $B$ is
(A) less
(B) greater
(C) the same

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Problem 10

Which phenomenon best supports the particle theory of light?
(A) photoelectric effect
(B) diffraction
(C) interference
(D) polarization

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Problem 11

A mercury atom in the ground state absorbs $20.00$ electronvolts of energy and is ionized by losing an electron. How much kinetic energy does this electron have after the ionization?
(A) $6.40 \mathrm{eV}$
(B) $9.62 \mathrm{eV}$
(C) $10.38 \mathrm{eV}$
(D) $13.60 \mathrm{eV}$

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Problem 12

Which graph best represents the relationship between photon energy and photon frequency?

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Problem 13

A variable-frequency light source emits a series of photons. As the frequency of the photon increases, what happens to the energy and wavelength of the photon?
(A) The energy decreases and the wavelength decreases.
(B) The energy decreases and the wavelength increases.
(C) The energy increases and the wavelength decreases.
(D) The energy increases and the wavelength increases.

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Problem 14

The slope of a graph of photon energy versus photon frequency represents
(A) Planck's constant
(B) the mass of a photon
(C) the speed of light
(D) the speed of light squared

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Problem 15

A photon having an energy of $9.40$ electronvolts strikes a hydrogen atom in the ground state. Why is the photon not absorbed by the hydrogen atom?
(A) The atom's orbital electron is moving too fast.
(B) The photon striking the atom is moving too fast.
(C) The photon's energy is too small.
(D) The photon is being repelled by electrostatic force.

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Problem 16

A photon of light traveling through space with a wavelength of $6.0 \times 10^{-7}$ meter has an energy of
(A) $4.0 \times 10^{-40} \mathrm{~J}$
(B) $3.3 \times 10^{-19} \mathrm{~J}$
(C) $5.4 \times 10^{10} \mathrm{~J}$
(D) $5.0 \times 10^{14} \mathrm{~J}$

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Problem 17

What is the net electrical charge on a magnesium ion that is formed when a neutral magnesium atom loses two electrons?
(A) $-3.2 \times 10^{-19} \mathrm{C}$
(B) $-1.6 \times 10^{-19} \mathrm{C}$
(C) $+1.6 \times 10^{-19} \mathrm{C}$
(D) $+3.2 \times 10^{-19} \mathrm{C}$

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Problem 18

Which type of photon is emitted when an electron in a hydrogen atom drops from $n=2$ to the $n=1$ energy level?
(A) ultraviolet
(B) visible light
(C) infrared
(D) radio wave

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Problem 19

Oil droplets may gain electrical charges as they are projected through a nozzle. Which quantity of charge is not possible on an oil droplet?
(A) $8.0 \times 10^{-19} \mathrm{C}$
(B) $4.8 \times 10^{-19} \mathrm{C}$
(C) $3.2 \times 10^{-19} \mathrm{C}$
(D) $2.6 \times 10^{-19} \mathrm{C}$

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Problem 20

All photons in a vacuum have the same
(A) speed
(B) wavelength
(C) energy
(D) frequency

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Problem 21

Which phenomenon best supports the theory that matter has a wave nature?
(A) electron momentum
(B) electron diffraction
(C) photon momentum
(D) photon diffraction

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Problem 22

The diagram below represents the bright-line spectra of four elements, $A, B, C$, and $D$, and the spectrum of an unknown gaseous sample.
Based on comparisons of these spectra, which two elements are found in the unknown sample?
(A) $A$ and $B$
(B) $A$ and $D$
(C) $B$ and $C$
(D) $C$ and $D$

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Problem 23

Base your answers to questions 23 through 25 on the diagram below, which represents monochromatic light incident upon photoemissive surface $A$. Each photon has $8.0 \times 10^{-19}$ joule of energy. $B$ represents the particle emitted when a photon strikes surface $A .$
What is particle $B$ ?
(A) an alpha particle
(B) an electron
(C) a neutron
(D) a proton

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Problem 24

If the work function of metal $A$ is $3.2 \times 10^{-19}$ joule, the energy of particle $B$ is
(A) $3.0 \times 10^{-19} \mathrm{~J}$
(B) $4.8 \times 10^{-19} \mathrm{~J}$
(C) $8.0 \times 10^{-19} \mathrm{~J}$
(D) $11 \times 10^{-19} \mathrm{~J}$

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Problem 25

The frequency of the incident light is approximately
(A) $1.2 \times 10^{15} \mathrm{~Hz}$
(B) $5 \cdot 3 \times 10^{15} \mathrm{~Hz}$
(C) $3.7 \times 10^{15} \mathrm{~Hz}$
(D) $8.3 \times 10^{15} \mathrm{~Hz}$

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Problem 26

Which occurs when a photon and a free electron collide?
(A) Momentum is conserved.
(B) Only the kinetic energy of the photon is conserved.
(C) The momentum of the photon is increased.
(D) The wavelength of the photon is unchanged.

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Problem 27

A gamma photon makes a collision with an electron at rest. During the interaction, the momentum of the photon will
(A) decrease
(B) increase
(C) remain the same

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Problem 28

If an X-ray photon collides with an electron, the frequency of the photon will
(A) decrease
(B) increase
(C) remain the same

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Problem 29

Base your answers to questions 29 through 32 on the information and diagram below.
An incident photon with a frequency of $5.0 \times 10^{16}$ hertz strikes a stationary electron. The scattered photon rebounds at an angle of $90^{\circ}$, and the electron moves away with a kinetic energy of $100 .$ electron-volts.
Which vector best represents the direction of motion of the electron after the collision?

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Problem 30

What is the energy of the incident photon?
(A) $1.3 \times 10^{-18} \mathrm{~J}$
(B) $5.0 \times 10^{-17} \mathrm{~J}$
(C) $5.0 \times 10^{16} \mathrm{~J}$
(D) $3 \cdot 3 \times 10^{-17} \mathrm{~J}$

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Problem 31

Compared to the speed of the incident photon, the speed of the scattered photon is
(A) smaller
(B) greater
(C) the same

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Problem 32

Compared to the wavelength of the incident photon, the wavelength of the scattered photon is
(A) shorter
(B) longer
(C) the same

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Problem 33

As the speed of an electron increases, its wavelength
(A) decreases
(B) increases
(C) remains the same

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Problem 34

In the Rutherford experiment, a beam of alpha particles was directed at a thin gold foil. The deflection pattern of the alpha particles showed that
(A) the electrons of gold atoms have waves
(B) the nuclear volume is a small part of the atomic volume
(C) the energy levels of a gold atom are quantized
(D) gold atoms can emit photons under bombardment

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Problem 35

According to the Rutherford model of the atom, the volume of an atom is composed mainly of
(A) electrons
(B) protons
(C) neutrons
(D) empty space

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Problem 36

Which type of force causes the hyperbolic trajectory of alpha particles in Rutherford's scattering experiment?
(A) gravitational
(B) electrostatic
(C) magnetic
(D) nuclear

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Problem 37

A scattering experiment is performed in which alpha particles from a single source are deflected by the nuclei of various atomic elements. The nuclei causing the greatest amount of alphaparticle scattering are those having the
(A) smallest neutron number
(B) greatest photon number
(C) smallest mass number
(D) greatest atomic number

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Problem 38

Rutherford observed that most of the alpha particles directed at a metallic foil appear to pass through unhindered, with only a few deflected at large angles. What did he conclude?
(A) Alpha particles behave like waves when they interact with atoms.
(B) Atoms have most of their mass distributed loosely in an electron cloud.
(C) Atoms can easily absorb and reemit alpha particles.
(D) Atoms consist mainly of empty space and have small, dense nuclei.

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Problem 39

High-speed alpha particles strike a metal foil. Which element, when used in the foil, will tend to scatter the alpha particles through the greatest angles?
(A) platinum, with 78 elementary charges per nucleus
(B) silver, with 47 elementary charges per nucleus
(C) copper, with 29 elementary charges per nucleus
(D) vanadium, with 23 elementary charges per nucleus

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Problem 40

Base your answers to questions 40 through 44 on Rutherford's experiments in which alpha particles were allowed to pass into a thin gold foil. All alpha particles had the same speed.
The paths of the scattered alpha particles were
(A) hyperbolic
(B) circular
(C) parabolic
(D) elliptical

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Problem 41

Some of the alpha particles were deflected. The explanation for this phenomenon is that
(A) electrons have a small mass
(B) electrons have a small charge
(C) the gold leaf was only a few atoms thick
(D) the nuclear charge and mass are concentrated in a small volume

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Problem 42

The alpha particles were scattered because of
(A) gravitational forces
(B) coulomb forces
(C) magnetic forces
(D) nuclear forces

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Problem 43

As the distance between the nuclei of the gold atoms and the paths of the alpha particles increases, the angle of scattering of the alpha particles
(A) decreases
(B) increases
(C) remains the same

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Problem 44

If a foil were used whose nuclei had a greater atomic number, the angle of scattering of the alpha particles would
(A) decrease
(B) increase
(C) remain the same

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Problem 45

In alpha-particle scattering, the nucleus produces an effect on the scattering angles. This is due primarily to the fact that the nucleus
(A) has a small total charge
(B) has a mass close to that of the alpha particles
(C) exerts coulomb forces
(D) is widely dispersed throughout the atom

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Problem 46

Which diagram best represents the path of a positively charged particle as it passes near the nucleus of an atom?

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Problem 47

As excited hydrogen atoms return to the ground state, they emit
(A) electrons
(B) protons
(C) photons
(D) neutrons

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Problem 48

As an electron orbits a nucleus in the same energy level, the energy of the electron
(A) decreases
(B) increases
(C) remains the same

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Problem 49

As the radius of an electron orbit in a Bohr atom increases, the magnitude of the energy of the atom
(A) decreases
(B) increases
(C) remains the same

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Problem 50

Which is a characteristic of both the Bohr and the Rutherford atomic model?
(A) Neutrons exist in the nuclei of all atoms.
(B) Only a limited number of specified orbits is permitted.
(C) The nucleus is concentrated in a small, dense core.
(D) Electron energy level changes are in discrete amounts.

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Problem 51

When a hydrogen atom changes from one energy level $\left(E_{1}\right)$ to a lower energy level $\left(E_{2}\right)$, the expression for the frequency of the emitted photon is
(A) $\frac{\mathbf{E}}{2}$
(B) $\frac{h \lambda}{E_{1}-E_{2}}$
(C) $\frac{h \lambda}{E_{1}-E_{2}}$
(D) $\left(E_{1}-E_{2}\right) \frac{\lambda}{2}$

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Problem 52

The lowest energy state of an atom is called its
(A) ground state
(B) ionized state
(C) initial energy state
(D) final energy state

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Problem 53

When an excited atom emits a photon, the total energy of the atom
(A) decreases
(B) increases
(C) remains the same

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Problem 54

When an electron changes from a higher energy state to a lower energy state within an atom, a quantum of energy is
(A) fissioned
(B) fused
(C) emitted
(D) absorbed

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Problem 55

According to the Bohr model of the atom, an electron in a stable orbit does not
(A) have potential energy
(B) emit radiation
(C) undergo acceleration
(D) have kinetic energy

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Problem 56

Which are emitted as atoms of a given element return to the ground state?
(A) electrons
(B) photons
(C) alpha particles
(D) neutrons

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Problem 57

In his model of the atom, Bohr assumed that the electrons
(A) are distributed evenly throughout the atom
(B) are located only in the nucleus of the atom
(C) are located only in a limited number of specified orbits
(D) emit energy while in orbit

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Problem 58

A hydrogen atom undergoes a transition from the $n=3$ state to the ground state. The total number of different possible photon energies that may be emitted is
(A) 1
(B) 2
(C) 3
(D) 4

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Problem 59

A photon with an energy of $10.2$ electron-volts is absorbed by a hydrogen atom. This may cause the energy state of the hydrogen atom to move from
(A) $n=1$ to $n=2$
(B) $n=1$ to $n=3$
(C) $n=1$ to $n=4$
(D) $n=1$ to $n=5$

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Problem 59

Base your answers to questions 69 and 70 on the Energy Levels for Hydrogen chart in the Physics Reference Tables.
Which photon could be absorbed by a hydrogen atom in the ground state?
(A) a $11.0-\mathrm{eV}$ photon
(B) a $10.2-\mathrm{eV}$ photon
(C) a $3.4$-eV photon
(D) a $0.54$-eV photon

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Problem 60

The energy needed to ionize a hydrogen atom in the ground state is
(A) $2.9 \mathrm{eV}$
(B) $3.2 \mathrm{eV}$
(C) $13.06 \mathrm{eV}$
(D) $13.6 \mathrm{eV}$

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Problem 61

What is the minimum amount of energy required to ionize a hydrogen atom in the $n=2$ state?
(A) $13.6 \mathrm{eV}$
(B) $10.2 \mathrm{eV}$
(C) $3.40 \mathrm{eV}$
(D) $\mathrm{O} \mathrm{eV}$

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Problem 62

An atom changing from an energy state of $-0.54 \mathrm{eV}$ to an energy state of $-0.85 \mathrm{eV}$ will emit a photon whose energy is
(A) $0.31 \mathrm{eV}$
(B) $0.54 \mathrm{eV}$
(C) $0.85 \mathrm{eV}$
(D) $1.39 \mathrm{eV}$

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Problem 63

A hydrogen atom can be raised from the $n=2$ state to the $n=3$ state by a photon with an energy of
(A) $1.89 \mathrm{eV}$
(B) $10.2 \mathrm{eV}$
(C) $12.1 \mathrm{eV}$
(D) $22.3 \mathrm{eV}$

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Problem 64

A hydrogen atom in the ground state receives $10.2$ electron-volts of energy. To which energy level may the atom become excited?
(A) $n=5$
(B) $n=2$
(C) $n=3$
(D) $n=4$

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Problem 65

A photon having an energy of $15.5$ electron-volts is incident upon a hydrogen atom in the ground state. The photon may be absorbed by the atom and
(A) ionize the atom
(B) excite the atom to $n=2$
(C) excite the atom to $n=3$
(D) excite the atom to $n=4$

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Problem 66

A hydrogen atom is in the $n=5$ energy state after having absorbed a $0.97-\mathrm{eV}$ photon. What was the original energy state of the hydrogen atom?
(A) $n=1$
(B) $n=2$
(C) $n=3$
(D) $n=4$

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Problem 67

A model of the atom in which the electrons can exist only in specified orbits was suggested by
(A) Bohr
(B) Planck
(C) Einstein
(D) Rutherford

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Problem 68

In a hydrogen atom the electron makes the following successive transitions:
$$n=5 \rightarrow n=4 \rightarrow n=3 \rightarrow n=2 \rightarrow n=1$$
The emitted photon energies for the successive transitions
(A) decrease
(B) increase
(C) remain the same

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Problem 70

Which energy-level jump would show as a bright line in the visible spectrum of hydrogen?
(A) 1 to 2
(B) 2 to 3
(C) 3 to 2
(D) 4 to 7

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Problem 71

A hydrogen atom, in the ground state, is bombarded by an 11electron-volt photon. Which statement best describes the interaction that occurs?
(A) The photon collides elastically and leaves the atom with an energy of 11 electron-volts.
(B) The photon collides inelastically and retains an energy of $0.8$ electron-volt.
(C) The photon collides inelastically and disappears.
(D) The atom is completely ionized to $\mathrm{a}+1$ ion, and the photon disappears.

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Problem 72

A photon with an energy of $20 .$ electron-volts is completely absorbed by a hydrogen atom in the ground state, ionizing the atom. What is the approximate energy of the incoming photon?
(A) $8.0 \times 10^{-20} \mathrm{~J}$
(B) $1.6 \times 10^{-19} \mathrm{~J}$
(C) $3.2 \times 10^{-18} \mathrm{~J}$
(D) $20 \mathrm{~J}$

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Problem 73

A hydrogen atom undergoes a transition from the $n=4$ state to the $n=1$ state. The energy of the single photon emitted during the transition is approximately
(A) $13.6 \mathrm{eV}$
(B) $12.75 \mathrm{eV}$
(C) $2.55 \mathrm{eV}$
(D) $0.85 \mathrm{eV}$

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Problem 74

Base your answers to questions 74 through 77 on the information and diagram below and on the Physics Reference Tables.
The diagram represents the model of the Bohr hydrogen atom in the ground state. The speed of the electron is $2.17 \times 10^{6}$ meters per second.
What is the kinetic energy of the electron in the ground state?
(A) $4.36 \times 10^{-18} \mathrm{~J}$
(B) $2.14 \times 10^{-18} \mathrm{~J}$
(C) $9.87 \times 10^{-24} \mathrm{~J}$
(D) 0

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Problem 75

Compared to the electrostatic force between the proton and the electron, the centripetal force on the electron is
(A) one-fourth as much
(B) one-half as much
(C) the same
(D) twice as much

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Problem 76

The electrostatic force between the electron and the proton is approximately
(A) $4.3 \times 10^{-18} \mathrm{~N}$
(B) $4.1 \times 10^{-8} \mathrm{~N}$
(C) $8.2 \times 10^{-8} \mathrm{~N}$
(D) $5.1 \times 10^{1} \mathrm{~N}$

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Problem 77

Compared to the electrostatic force between the proton and the electron, the gravitational force between them is
(A) less
(B) greater
(C) the same

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Problem 78

Base your answers to questions 78 and 79 on the diagram below, which shows some of the energy levels of a mercury atom. The range of the energies of visible photons is approximately $1.5 \mathrm{eV}$ to $3.0 \mathrm{eV}$
Which energy level transition would cause the emission of visible photons?
(A) from $-5.5 \mathrm{eV}$ to $-10.4 \mathrm{eV}$
(B) from $-3.7 \mathrm{eV}$ to $-5 \cdot 5 \mathrm{eV}$
(C) from $-3.7 \mathrm{eV}$ to $-1.6 \mathrm{eV}$
(D) from $-5.5 \mathrm{eV}$ to $-1.6 \mathrm{eV}$

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Problem 79

The minimum energy required to ionize a mercury atom in the ground state is
(A) $4.9 \mathrm{eV}$
(B) $6.7 \mathrm{eV}$
(C) $8.8 \mathrm{eV}$
(D) $10.4 \mathrm{eV}$

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Problem 80

A photon with a wavelength of $6.0 \times 10^{-7}$ meter would have an energy of
(A) $9.4 \times 10^{-20} \mathrm{~J}$
(B) $3.3 \times 10^{-19} \mathrm{~J}$
(C) $6.0 \times 10^{-7} \mathrm{~J}$
(D) $9.4 \times 10^{18} \mathrm{~J}$

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Problem 81

A $3.0$-electron-volt photon would have a wavelength of approximately
(A) $4 \times 10^{-7} \mathrm{~m}$
(B) $5 \times 10^{-7} \mathrm{~m}$
(C) $6 \times 10^{-7} \mathrm{~m}$
(D) $7 \times 10^{-7} \mathrm{~m}$

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Problem 82

Base your answer to question 82 on the cartoon below and your knowledge of physics.
In the cartoon, Einstein is contemplating the equation for the principle that
(A) the fundamental source of all energy is the conversion of mass into energy
(B) energy is emitted or absorbed in discrete packets called photons
(C) mass always travels at the speed of light in a vacuum
(D) the energy of a photon is proportional to its frequency

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