Question 1

When light is absorbed by a metal,the energy of each light quantum is usually given to several adjacent electrons.

Accepted Answer

A) True 
 B)False  False

Question 2

An electron has the same de Broglie wavelength as a 1.8 eV photon.The speed of the electron is closest to:

Accepted Answer

A) 1100 m/s 
B) 980 m/s 
C) 910 m/s 
D) 840 m/s 
E) 770 m/s 
A) 1100 m/s 
B) 980 m/s 
C) 910 m/s 
D) 840 m/s 
E) 770 m/s A

Question 3

A quantum of blue light carries more energy than a quantum of red light.

Accepted Answer

A) True 
 B)False  True

Question 4

A photocathode has a work function of 2.4 eV.The photocathode is illuminated with monochromatic radiation whose photon energy is 3.4 eV.The maximum kinetic energy of the photoelectrons produced is closest to:

Accepted Answer

A) 1.6 × 10-19 J 
B) 3.8 × 10-19 J 
C) 4.4 × 10-19 J 
D) 4.9 × 10-19 J 
E) 5.4 × 10-19 J 
A) 1.6 × 10-19 J 
B) 3.8 × 10-19 J 
C) 4.4 × 10-19 J 
D) 4.9 × 10-19 J 
E) 5.4 × 10-19 J

Question 5

Gamma rays are photons with very high energy.How many visible-light photons with a wavelength of 500 nm would you need to match the energy of a gamma-ray photon with energy 4.1 F1F1F1S1F1F1F10 10-13 J?

Accepted Answer

A) 1.0 × 106 
B) 1.4 × 108 
C) 6.2 × 109 
D) 3.9 × 103 
A) 1.0 × 106 
B) 1.4 × 108 
C) 6.2 × 109 
D) 3.9 × 103

Question 6

The work function of a particular substance is 4.20 F1F1F1S1F1F1F10 10-19J.What is the photoelectric cutoff wavelength for this material?

Accepted Answer

A) 473 nm 
B) 308 nm 
C) 393 nm 
D) 554 nm 
A) 473 nm 
B) 308 nm 
C) 393 nm 
D) 554 nm

Question 7

Increasing the kinetic energy of an electron increases its de Broglie wavelength.

Accepted Answer

A) True 
 B)False

Question 8

A photocathode whose work function is 2.9 eV is illuminated with white light that has a continuous wavelength band from 400 nm to 700 nm.The range of the wavelength band in this white light illumination for which photoelectrons are not produced,in nm,is closest to:

Accepted Answer

A) 430 to 700 
B) 400 to 480 
C) 430 to 480 
D) 400 to 430 
E) 480 to 700 
A) 430 to 700 
B) 400 to 480 
C) 430 to 480 
D) 400 to 430 
E) 480 to 700

Question 9

Find the energy (in eV)of an optical photon of frequency 6.43 F1F1F1S1F1F1F10 1014Hz.

Accepted Answer

A) 2.66 eV 
B) 1.62 eV 
C) 1.94 eV 
D) 3.27 eV 
A) 2.66 eV 
B) 1.62 eV 
C) 1.94 eV 
D) 3.27 eV

Question 10

A photon collides with an electron that is initially at rest,causing the electron to move.After the collision,the wavelength of the photon is

Accepted Answer

A) greater than its initial value. 
B) equal to its initial value. 
C) less than its initial value. 
A) greater than its initial value. 
B) equal to its initial value. 
C) less than its initial value.

Question 11

Find the de Broglie wavelength of a 1.30 kg object moving a 28.10 m/s.

Accepted Answer

A) 1.81 × 10-35 m 
B) 2.05 × 10-35 m 
C) 2.29 × 10-35 m 
D) 2.58 × 10-35 m 
A) 1.81 × 10-35 m 
B) 2.05 × 10-35 m 
C) 2.29 × 10-35 m 
D) 2.58 × 10-35 m

Question 12

To say that a particle's energy is "quantized" means that it can have only certain discrete values.

Accepted Answer

A) True 
 B)False

Question 13

A friend in your physics class tells you that illuminating a surface with any laser will result in the emission of photoelectrons,as long as the illumination lasts long enough to supply the needed energy.Is she correct? Support your answer.

Accepted Answer

Your friend is not correct.Under the pro

Question 14

A crystal is irradiated with X-ray photons with energies of 1.65 × 10-15 J.The atomic planes in the crystal are separated by 0.21 nm.At what angles of incidence will the X-rays reflect from the crystal?

Accepted Answer

A) 73°,55°,and 31° 
B) 55° 
C) 73° and 31° 
D) 73° 
A) 73°,55°,and 31° 
B) 55° 
C) 73° and 31° 
D) 73°

Question 15

The frequency of light is the number of photons per second that it carries.

Accepted Answer

A) True 
 B)False

Question 16

Increasing the brightness of a beam of light without changing its color will increase

Accepted Answer

A) the number of photons emitted by light every second. 
B) the average energy of each photon. 
C) the speed of the photons. 
D) Two of the above statements are true. 
A) the number of photons emitted by light every second. 
B) the average energy of each photon. 
C) the speed of the photons. 
D) Two of the above statements are true.

Question 17

For what wavelength does a 100 mW laser deliver 1.6 × 1017 photons in one second?

Accepted Answer

A) 320 nm 
B) 330 nm 
C) 340 nm 
D) 350 nm 
A) 320 nm 
B) 330 nm 
C) 340 nm 
D) 350 nm

Question 18

Electrons are accelerated to a speed of 4.0 × 104 m/s and are aimed at a double-slit apparatus.Interference fringes are detected.If the electrons were replaced by neutrons,what speed must neutrons have to produce interference fringes with the same fringe spacing as that observed with the electrons?

Accepted Answer

A) 2.2 × 101 m/s 
B) 7.3 × 107 m/s 
C) 1.7 × 106 m/s 
D) 9.3 × 102 m/s 
A) 2.2 × 101 m/s 
B) 7.3 × 107 m/s 
C) 1.7 × 106 m/s 
D) 9.3 × 102 m/s

Question 19

The threshold frequency of a metal is the largest frequency of light that will dislodge photoelectrons from this metal.

Accepted Answer

A) True 
 B)False

Question 20

An electron is contrained to be inside a one-dimensional box.If the length of the box is doubled,the minimum energy of the electron

Accepted Answer

A) decreases by a factor of four. 
B) decreases by a factor of two. 
C) does not change. 
D) is zero,regardless of the the size of the box. 
A) decreases by a factor of four. 
B) decreases by a factor of two. 
C) does not change. 
D) is zero,regardless of the the size of the box.

Exam 28: Quantum Physics

When light is absorbed by a metal,the energy of each light quantum is usually given to several adjacent electrons.

An electron has the same de Broglie wavelength as a 1.8 eV photon.The speed of the electron is closest to:

A quantum of blue light carries more energy than a quantum of red light.

A photocathode has a work function of 2.4 eV.The photocathode is illuminated with monochromatic radiation whose photon energy is 3.4 eV.The maximum kinetic energy of the photoelectrons produced is closest to:

Gamma rays are photons with very high energy.How many visible-light photons with a wavelength of 500 nm would you need to match the energy of a gamma-ray photon with energy 4.1  10-13 J?

The work function of a particular substance is 4.20  10-19J.What is the photoelectric cutoff wavelength for this material?

Increasing the kinetic energy of an electron increases its de Broglie wavelength.

A photocathode whose work function is 2.9 eV is illuminated with white light that has a continuous wavelength band from 400 nm to 700 nm.The range of the wavelength band in this white light illumination for which photoelectrons are not produced,in nm,is closest to:

Find the energy (in eV)of an optical photon of frequency 6.43  1014Hz.

A photon collides with an electron that is initially at rest,causing the electron to move.After the collision,the wavelength of the photon is

Find the de Broglie wavelength of a 1.30 kg object moving a 28.10 m/s.

To say that a particle's energy is "quantized" means that it can have only certain discrete values.

A friend in your physics class tells you that illuminating a surface with any laser will result in the emission of photoelectrons,as long as the illumination lasts long enough to supply the needed energy.Is she correct? Support your answer.

A crystal is irradiated with X-ray photons with energies of 1.65 × 10-15 J.The atomic planes in the crystal are separated by 0.21 nm.At what angles of incidence will the X-rays reflect from the crystal?

The frequency of light is the number of photons per second that it carries.

Increasing the brightness of a beam of light without changing its color will increase

For what wavelength does a 100 mW laser deliver 1.6 × 1017 photons in one second?

The threshold frequency of a metal is the largest frequency of light that will dislodge photoelectrons from this metal.

An electron is contrained to be inside a one-dimensional box.If the length of the box is doubled,the minimum energy of the electron

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Gamma rays are photons with very high energy.How many visible-light photons with a wavelength of 500 nm would you need to match the energy of a gamma-ray photon with energy 4.1  10^-13 J?

The work function of a particular substance is 4.20  10^-19J.What is the photoelectric cutoff wavelength for this material?

Find the energy (in eV)of an optical photon of frequency 6.43  10¹⁴Hz.

A crystal is irradiated with X-ray photons with energies of 1.65 × 10^-15 J.The atomic planes in the crystal are separated by 0.21 nm.At what angles of incidence will the X-rays reflect from the crystal?

For what wavelength does a 100 mW laser deliver 1.6 × 10¹⁷ photons in one second?