Deck 28: Quantum Theory

Question 1

According to Einstein, as the wavelength of the incident monochromatic light beam becomes shorter, the work function of a target material in a phototube:

A) increases.
B) is directly proportional to wavelength.
C) decreases.
D) remains constant.

Answer 1

remains constant.

Question 2

The ultraviolet catastrophe predicts that:

A) a black body can absorb an infinite amount of radiation if the radiation is in the ultraviolet region.
B) the radiated energy approaches zero as the wavelength approaches zero.
C) as an object gets hotter its light will change from dull red to blue white.
D) all objects should radiate extreme amounts of ultraviolet light.

Answer 2

all objects should radiate extreme amounts of ultraviolet light.

Question 3

If a monochromatic light beam with quantum energy value of 4.0 eV is incident upon a photocell where the work function of the target metal is 1.60 eV, what is the maximum kinetic energy of ejected electrons?

A) 4.6 eV
B) 4.8 eV
C) 2.4 eV
D) 1.4 eV

Answer 3

2.4 eV

Question 4

What is the wavelength of a monochromatic light beam, where the photon energy is 2.00 eV? (h = 6.63 *10^-34 J.s, c = 3.00 *10⁸ m/s, 1 nm = 10^-9 m, and 1 eV = 1.6 *10^-19 J)

A) 414 nm
B) 1243 nm
C) 311 nm
D) 622 nm

Question 5

Light of wavelength 6.1 *10^-7 m has an energy of: (h = 6.63 *10^-34 J.s, c = 3.00 * 10⁸ m/s)

A) 3.1 *10^-19 J
B) 1.5 *10^-19 J
C) 1.7 *10^-19 J
D) 3.3 *10^-19 J

Question 6

According to Wien's displacement law, if the absolute temperature of a radiating blackbody is doubled, then the peak wavelength emitted will change by what factor?

A) 4
B) 2
C) 1
D) 1/2

Question 7

What is the wavelength of a monochromatic light beam, where the photon energy is 4.81 *10^-19 J? (h = 6.63 *10^-34 J.s, c = 3.00 *10⁸ m/s, and 1 nm = 10^-9 m)

A) 354 nm
B) 414 nm
C) 787 nm
D) 398 nm

Question 8

Of photons of red, yellow, light, and blue light, which photons have the least energy?

A) red
B) blue
C) green
D) yellow

Question 9

If a blackbody is at 2000° C, what will be the peak wavelength emitted?

A) 1.67 $\mu$ m
B) 1.28 $\mu$ m
C) 0.679 $\mu$ m
D) 1.45 $\mu$ m

Question 10

If a quantum of radiation has an energy of 3.0 keV, what is its wavelength? (h = 6.63 *10^-34 J.s, 1 eV = 1.60 *10^-19 J, c = 3.00 *10⁸ m/s, and 1 nm = 10^-9 m)

A) 0.62 nm
B) 0.32 nm
C) 0.41 nm
D) 1.02 nm

Question 11

Surface #1 has work function , and when bombarded with photons of wavelength emits photoelectrons with maximum energy . Surface #2 has work function , and when bombarded by photons of wavelength emits photoelectrons with maximum energy . If , then which of the following must be true?

A)
B) for surface #1 is greater than for surface #2.
C) for surface #2 is greater than for surface #1.
D)

Question 12

What is the surface temperature of a distant star (which emits light as if it were a blackbody) where the peak wavelength is 456 nm? (Hint: The surface of the human body at 35° C has a peak wavelength of 9.41 $\mu$ m). (1 nm = 10 ^{- 9} m = 10^-3 $\mu$ m)

A) 5100 K
B) 4510 K
C) 6040 K
D) 6360 K

Question 13

Blue light will not eject electrons from a certain metal; however, which one of the following may possibly eject electrons from that metal?

A) red
B) green
C) infrared
D) ultraviolet

Question 14

As the temperature of a radiation emitting blackbody becomes lower, what happens to the peak wavelength of the radiation?

A) remains constant
B) increases
C) decreases
D) is directly proportional to temperature

Question 15

What is the frequency of monochromatic light where the photon energy is 6.5 *10^-19 J? (h = 6.63 *10^-34 J.s)

A) 2.2 *10¹⁴ Hz
B) 9.8 * 10¹⁴ Hz
C) 4.4 *10¹⁴ Hz
D) 8.3 *10¹⁴ Hz

Question 16

Which of the following is an indication that one is dealing with a wave property instead of a particle property?

A) energy
B) quanta
C) interference
D) momentum

Question 17

A quantum of radiation has an energy of 1.3 keV. What is its frequency? (h = 6.63 *10^-34 J.s and 1 eV = 1.60 *10^-19 J)

A) 6.3 *10¹⁷ Hz
B) 3.1 * 10¹⁷ Hz
C) 4.8 * 10¹⁷ Hz
D) 7.2 * 10¹⁷ Hz

Question 18

Star A has the peak of its blackbody radiation at $\lambda$ _A. Star B has its peak at $\lambda$ _B, which is one-third that of $\lambda$ _A. If Star A's surface temperature is T_A, how does the surface temperature T_B of Star B compare?

A) T_B = T_A/9
B) T_B = 3 T_A
C) T_B = 9 T_A
D) T_B = T_A/3

Question 19

Classical theories predict that most of the energy from a blackbody should be radiated:

A) at the wavelength given by Wien's displacement law.
B) as thermal radiation in the infrared region.
C) a blackbody should not radiate.
D) as ultraviolet light.

Question 20

Planck's quantum theory is compatible with the experimental data related to which of the following?

A) line spectra emitted by hydrogen gas
B) the photoelectric effect
C) blackbody radiation
D) all of these choices

Question 21

Who was the first to successfully explain the photoelectric effect?

A) Young
B) Einstein
C) Planck
D) Bohr

Question 22

A light-emitting diode has a power output of 0.3 W. If 590 nm is the average wavelength of the source, about how many photons are emitted per second? (h = 6.63 *10^-34 J.s, c = 3.00 *10⁸ m/s, and 1 nm = 10^-9 m)

A) 10²¹
B) 10²⁵
C) 10¹⁸
D) 10²⁹

Question 23

According to Einstein, increasing the brightness of a beam of light without changing its color will increase:

A) the frequency of the photons.
B) the energy of each photon.
C) the speed of the photons.
D) the number of photons.

Question 24

Sources of red, blue, and yellow light each emit light with a power of 50 mW. Which source emits the least photons per second?

A) the red source
B) They all emit the same number per second.
C) the blue source
D) the yellow source

Question 25

Which change will not affect the kinetic energy of the most energetic electrons emitted in the photoelectric effect?

A) changing the frequency of the light
B) changing the metal the light is hitting
C) changing the brightness of the light
D) All of the above will affect the electron's kinetic energy.

Question 26

The microwave in the kitchen has a label that indicates it produces its microwaves at a frequency of 2450 MHz. What is the energy associated with one of these microwave photons? (h = 6.63 *10^-34 J.s)

A) eV
B) 2.45 eV
C) eV
D) 1.62 eV

Question 27

Blue light ( $\lambda$ = 460 nm) is incident on a piece of potassium (W = 2.45 eV). What is the maximum kinetic energy of the ejected photoelectrons? (h = 6.63 * 10^-34 J.s, c = 3.00 * 10⁸ m/s, 1 eV = 1.60 *10^-19 J, and 1 nm = 10^-9 m)

A) 1.0 eV
B) 0.25 eV
C) 0.50 eV
D) 4.9 eV

Question 28

What is the maximum velocity of a photoelectron emitted from a surface with work function 5.22 eV when illuminated by 200-nm ultraviolet light? (m_electron = 9.11 *10^-31 kg, h = 6.63 *10^-34 J.s, 1 eV = 1.60 *10^-19 J, and 1 nm = 10^-9 m)

A) 800,000 m/s
B) 212,000 m/s
C) 653,000 m/s
D) 591,000 m/s

Question 29

According to the de Broglie hypothesis, which of the following statements is applicable to the wavelength of a moving particle?

A) directly proportional to its momentum
B) inversely proportional to its energy
C) inversely proportional to its momentum
D) directly proportional to its energy

Question 30

Which of the following statements best describes the relation between quantum theory and the photoelectric effect experiment?

A) The photoelectric effect contradicts quantum theory.
B) Quantum theory explains the photoelectric effect.
C) Quantum theory has no bearing on the photoelectric effect.
D) The photoelectric effect explains quantum theory.

Question 31

Of the following energies for photons, which is the least energy that could result in photoelectron production if the work function is 1.60 eV?

A) 1.50 eV
B) 6.01 eV
C) 2.90 eV
D) 3.50 eV

Question 32

A proton and an electron each have the same de Broglie wavelength. (i) Which has the lower speed, and (ii) which has the lower kinetic energy?

A) (i) the electron, (ii) the electron
B) (i) the electron, (ii) Either one can have the greater kinetic energy.
C) (i) the proton, (ii) Either one can have the greater kinetic energy.
D) (i) the proton, (ii) the proton

Question 33

A helium-neon laser emits red light having a wavelength of 632.8 nm and a power of 10 mW. How many photons are emitted each second? (h = 6.63 *10^-34 J.s, c = 3.00 * 10⁸ m/s, and 1 nm = 10^-9 m)

A) 4.8 * 10¹⁷
B) 1.6 *10¹⁵
C) 3.2 * 10¹⁶
D) 2.6 *10¹⁸

Question 34

What is the energy of a photon whose frequency is 7.9 *10²⁰ Hz? (h = 6.63 *10 ^{- 34} J.s and 1 eV = 1.60*10 ^{- 19} J)

A) 5.0 MeV
B) 3.3 MeV
C) 1.6 MeV
D) 2.5 MeV

Question 35

If a ¹H nucleus, a ²H nucleus, and a ³H nucleus all had the same momentum, which one has the lowest de Broglie wavelength?

A) "³H"
B) "²H"
C) "¹H"
D) "All three have the same de Broglie wavelength."

Question 36

A detector absorbs photons of monochromatic light and their total energy is found to be 33 nJ. What is the wavelength associated with these photons? (h = 6.63 *10^-34 J.s, c = 3.00 * 10⁸ m/s)

A) 600 nm
B) 540 nm
C) 400 nm
D) 500 nm

Question 37

How much energy (in eV) does a photon of 500-nm light have? (h = 6.63 * 10^-34 J.s, c = 3.00 * 10⁸ m/s, 1 eV = 1.60 *10^-19 J, and 1 nm = 10^-9 m)

A) 1.78 eV
B) 2.48 eV
C) 1.24 eV
D) 3.11 eV

Question 38

According to de Broglie, as the momentum of a moving particle is quartered, the corresponding wavelength changes by what factor?

A) 1/4
B) 1/16
C) 16
D) 4

Question 39

Of the following photons, which has the lowest energy?

A) visible
B) ultraviolet
C) infrared
D) microwave

Question 40

What is the de Broglie wavelength for a proton (m = 1.67 * 10^-27 kg) moving at a speed of 3.0 * 10⁶ m/s? (h = 6.63 *10^-34 J.s)

A) 0.33 *10^-13 m
B) 1.3 *10^-13 m
C) 0.66 *10^-13 m
D) 2.0 *10^-13 m

Question 41

If the measured momentum of an electron is 3.20 *10^-27 kg.m/s with an uncertainty of 4.8 *10^-28 kg.m/s, what is the minimum uncertainty in the position? (h = 6.63 * 10^-34 J.s)

A) 0.63 * 10^-4 m
B) 2.2 *10^-7 m
C) 3.3 *10^-6 m
D) 1.1 * 10^-7 m

Question 42

What is the energy of a photon that has the same wavelength as a 24 eV electron? (h = 6.63 *10^-34 J.s, m_e = 9.11*10^-31 kg)

A) 24 eV
B) 14 * 10^-16 eV
C) 3.5 keV
D) 5.0 keV

Question 43

That light has a dual nature is referring to light:

A) having energy and momentum.
B) acting as waves and particles.
C) having high- or low-energy photons.
D) undergoing pair production.

Question 44

According to Heisenberg, as the uncertainty in the measurement of a particle's momentum is increased by a factor of 2, by what factor is the uncertainty in that particle's position changed?

A) 1
B) 4
C) 1/2
D) 2

Question 45

When stands for Planck's constant, what does (read as "h bar") stand for?

A) The bar means that we are only referring to spin angular momentum.
B) The bar means that the is divided by .
C) The bar means that it is negative, i.e., the same as .
D) The bar means that we are talking about angular momentum.

Question 46

Due to the dual nature of light and matter, either can act in an experiment as if it is a wave or a particle. In which experiment is the wave aspect exhibited for matter?

A) the Davisson and Germer experiment
B) Wien's law determinations
C) the Stern-Gerlach experiment
D) the photoelectric effect

Question 47

A proton (mass = 1.67 *10 ^{- 27} kg) has a kinetic energy of 1.00 MeV. If its momentum is measured with an uncertainty of 2.00%, what is the minimum uncertainty in its position? (h = 6.63 *10 ^{- 34} J.s and 1 eV = 1.6 *10 ^{- 19} J)

A) 9.08 * 10 ^{- 14} m
B) 1.14 *10 ^{- 13} m
C) 5.64 *10 ^{- 14} m
D) 2.28 * 10 ^{- 13} m

Question 48

If an electron has a measured wavelength of 1.20 *10 ^{- 10} m, what is its kinetic energy? (h = 6.63 * 10 ^{- 34} J.s, 1 eV = 1.6 *10 ^{- 19} J, and m_e = 9.11 *10 ^{- 31} kg)

A) 209 eV
B) 55.0 eV
C) 105 eV
D) 147 eV

Question 49

When an electron is in a magnetic field, different spin states associated with the electron's magnetic moment will occur. What are these states called?

A) up, down
B) plus, minus
C) clockwise, counterclockwise
D) north, south

Question 50

Starting from rest, an electron accelerates through a potential difference of 67 V. What is its de Broglie wavelength? (h = 6.63 *10 ^{- 34} J.s, m_e = 9.11 *10 ^{- 31} kg, and 1 eV = 1.60 *10 ^{- 19} J)

A) 1.1 *10 ^{- 10} m
B) 1.5 *10 ^{- 10} m
C) 1.9 *10 ^{- 10} m
D) 2.3 *10 ^{- 10} m

Question 51

When electrons are placed in a magnetic field, their spin orientations are quantized. How many orientations with respect to the field may result?

A) 1
B) 2
C) 3
D) 4 or more

Question 52

The wave function as derived in Schrödinger's equation is best described as being a measure of which of the following?

A) particle wavelength
B) photon wavelength
C) probability
D) photon beam frequency

Question 53

An electron and an alpha particle (a helium-4 nucleus) each have the same non-relativistic speed. Which has the greatest kinetic energy, and which has the shortest de Broglie wavelength?

A) the alpha particle, the alpha particle
B) the alpha particle, the electron
C) the electron, the alpha particle
D) the electron, the electron

Question 54

In the STM, what are the S and T?

A) scattering, transparent
B) superconducting, trans-barrier
C) standard, transmission
D) scanning, tunneling

Question 55

The "seeing" ability or resolution of radiation is determined by its wavelength. If the size of an atom is approximately 10^-10 m, how fast must an electron travel to have a wavelength smaller than that of an atom? (m_e = 9.11 *10^-31 kg and h = 6.63 *10^-34 J.s)

A) 1.0 *10⁶ m/s
B) 7.3 *10⁶ m/s
C) 5.4 *10⁵ m/s
D) 3.4 * 10⁶ m/s

Question 56

The uncertainty principle was derived by whom?

A) Heisenberg
B) Schrödinger
C) Gerlach
D) de Broglie

Question 57

What potential difference is needed to accelerate a proton from rest to give it a wavelength of m?

A) 411 V
B) 206 V
C) 1650 V
D) 617 V

Question 58

The Heisenberg uncertainty principle places restriction on the precision of simultaneously measuring both position and momentum. This principle can also be applied to the simultaneous measurement of two other variables, which are:

A) mass and charge.
B) torque and frequency.
C) force and color.
D) energy and time interval.

Question 59

The de Broglie wavelength of a 0.060-kg golf ball is 3.56 *10^-34 m. What is its speed? (h = 6.63 *10^-34 J.s)

A) 31 m/s
B) 15 m/s
C) 26 m/s
D) 48 m/s

Question 60

An electron microscope operates with electrons of kinetic energy 100 keV. What is the wavelength of these electrons? Assume this speed is not relativistic. (h = 6.63 *10 ^{- 34} J.s, c = 3.00 * 10⁸ m/s, 1 eV = 1.60 *10 ^{- 19} J, and m_e = 9.11 *10 ^{- 31} kg)

A) 5.49 *10 ^{- 12} m
B) 7.14 *10 ^{- 11} m
C) 9.28*10 ^{- 10} m
D) 3.88 *10 ^{- 12} m

Question 61

If the barrier width for an STM is 0.1 nm, what would be the corresponding minimum momentum uncertainty of an electron traversing this boundary?

A) 10^-25 kg·m/s
B) 10^-23 kg·m/s
C) 10^-24 kg·m/s
D) 10^-22 kg·m/s

Question 62

Which of the following is most sensitive to low-intensity light?

A) the green cones
B) the blue cones
C) the red cones
D) the rods

Question 63

If it takes 50 photons per 0.1 s entering the eye so that the brain senses the light, which of the following colors of light would be delivering the most power to the eye at this minimum perception level?

A) red
B) violet
C) blue
D) All would be delivering the same power.