Question 1

What is the wavelength of the matter wave associated with an electron moving with a speed of 2.5 × 107 m/s? (melectron = 9.11 × 10-31 kg,h = 6.626 × 10-34 J ∙ s)

Accepted Answer

A) 29 pm 
B) 35 pm 
C) 47 pm 
D) 53 pm 
A) 29 pm 
B) 35 pm 
C) 47 pm 
D) 53 pm

Question 2

Monochromatic light is incident on a metal surface,and the ejected electrons give rise to a current in the circuit shown in the figure.The maximum kinetic energy of the ejected electrons is determined by applying a reverse ('stopping')potential,sufficient to reduce the current in the ammeter to zero.If the intensity of the incident light is increased,how will the required stopping potential change?

Accepted Answer

A) It will remain unchanged. 
B) It will increase. 
C) It will decrease. 
A) It will remain unchanged. 
B) It will increase. 
C) It will decrease.

Question 3

What is the de Broglie wavelength of a ball of mass 200 g moving at 30 m/s? (h = 6.626 × 10-34 J ∙ s)

Accepted Answer

A) 1.1 × 10-34 m 
B) 2.2 × 10-34 m 
C) 4.5 × 10-28 m 
D) 6.7 × 10-27 m 
A) 1.1 × 10-34 m 
B) 2.2 × 10-34 m 
C) 4.5 × 10-28 m 
D) 6.7 × 10-27 m

Question 4

A photocathode that has a work function of 2.4 eV is illuminated with monochromatic light having photon energy 3.5 eV.What is the wavelength of this light? (c = 3.00 × 108 m/s,h = 6.626 × 10-34 J ∙ s,1 eV = 1.60 × 10-19 J)

Accepted Answer

A) 350 nm 
B) 330 nm 
C) 300 nm 
D) 380 nm 
E) 410 nm 
A) 350 nm 
B) 330 nm 
C) 300 nm 
D) 380 nm 
E) 410 nm

Question 5

An electron has the same de Broglie wavelength as the wavelength of a 1.8 eV photon.What is the speed of the electron? (melectron = 9.11 × 10-31 kg,c = 3.00 × 108 m/s,1 eV = 1.60 × 10-19 J)

Accepted Answer

A) 1,100 m/s 
B) 980 m/s 
C) 910 m/s 
D) 840 m/s 
E) 770 m/s 
A) 1,100 m/s 
B) 980 m/s 
C) 910 m/s 
D) 840 m/s 
E) 770 m/s

Question 6

A blue laser beam is incident on a metallic surface,causing electrons to be ejected from the metal.If the frequency of the laser beam is increased while the intensity of the beam is held fixed,

Accepted Answer

A) the rate of ejected electrons will decrease and their maximum kinetic energy will increase. 
B) the rate of ejected electrons will remain the same but their maximum kinetic energy will increase. 
C) the rate of ejected electrons will increase and their maximum kinetic energy will increase. 
D) the rate of ejected electrons will remain the same but their maximum kinetic energy will decrease. 
A) the rate of ejected electrons will decrease and their maximum kinetic energy will increase. 
B) the rate of ejected electrons will remain the same but their maximum kinetic energy will increase. 
C) the rate of ejected electrons will increase and their maximum kinetic energy will increase. 
D) the rate of ejected electrons will remain the same but their maximum kinetic energy will decrease.

Question 7

What is the frequency of the most intense radiation from an object with temperature 100°C? The constant in Wien's law is 0.0029 m ∙ K.(c = 3.0 × 108 m/s)

Accepted Answer

A) 2.9 × 10-5 Hz 
B) 3.9 × 1013 Hz 
C) 1.0 × 1013 Hz 
D) 1.0 × 1011 Hz 
A) 2.9 × 10-5 Hz 
B) 3.9 × 1013 Hz 
C) 1.0 × 1013 Hz 
D) 1.0 × 1011 Hz

Question 8

Find the de Broglie wavelength of a 1.30-kg missile moving at  
(h = 6.626 × 10-34 J ∙ s)

Accepted Answer

A) 1.81 × 10-35 m 
B) 2.05 × 10-35 m 
C) 2.28 × 10-35 m 
D) 2.57 × 10-35 m 
A) 1.81 × 10-35 m 
B) 2.05 × 10-35 m 
C) 2.28 × 10-35 m 
D) 2.57 × 10-35 m

Question 9

If the de Broglie wavelength of an electron is 380 nm,what is the speed of this electron? (melectron = 9.11 × 10-31 kg,h = 6.626 × 10-34 J ∙ s)

Accepted Answer

A) 2.0 km/s 
B) 3.8 km/s 
C) 1.9 km/s 
D) 4.1 km/s 
E) 5.2 km/s 
A) 2.0 km/s 
B) 3.8 km/s 
C) 1.9 km/s 
D) 4.1 km/s 
E) 5.2 km/s

Question 10

When it is struck by 240-nm photons,a metal ejects electrons with a maximum kinetic energy of  
What is the work function of this material? (c = 3.00 × 108 m/s,h = 6.626 × 10-34 J ∙ s,1 eV = 16.0 × 10-19 J)

Accepted Answer

A) 2.60 eV 
B) 2.18 eV 
C) 3.02 eV 
D) 3.43 eV 
A) 2.60 eV 
B) 2.18 eV 
C) 3.02 eV 
D) 3.43 eV

Question 11

An electron is moving with the speed of 1780 m/s.What is its de Broglie wavelength? (melectron = 9.11 × 10-31 kg,h = 6.626 × 10-34 J ∙ s)

Accepted Answer

A) 409 nm 
B) 302 nm 
C) 205 nm 
D) 420 nm 
E) 502 nm 
A) 409 nm 
B) 302 nm 
C) 205 nm 
D) 420 nm 
E) 502 nm

Question 12

A beam of light falling on a metal surface is causing electrons to be ejected from the surface.If we now double the frequency of the light,which of the following statements are correct? (There could be more than one correct choice. )

Accepted Answer

A) The kinetic energy of the ejected electrons doubles. 
B) The speed of the ejected electrons doubles. 
C) The number of electrons ejected per second doubles. 
D) Twice as many photons hit the metal surface as before. 
E) None of the above things occur. 
A) The kinetic energy of the ejected electrons doubles. 
B) The speed of the ejected electrons doubles. 
C) The number of electrons ejected per second doubles. 
D) Twice as many photons hit the metal surface as before. 
E) None of the above things occur.

Question 13

Monochromatic light falls on a metal surface and electrons are ejected.If the intensity of the light is increased,what will happen to the ejection rate and maximum energy of the electrons?

Accepted Answer

A) greater rate;same maximum energy 
B) same rate;greater maximum energy 
C) greater rate;greater maximum energy 
D) same rate;same maximum energy 
A) greater rate;same maximum energy 
B) same rate;greater maximum energy 
C) greater rate;greater maximum energy 
D) same rate;same maximum energy

Question 14

If the wavelength of a photon in vacuum is the same as the de Broglie wavelength of an electron,which one is traveling faster through space?

Accepted Answer

A) The electron because it has more mass. 
B) The photon because photons always travel through space faster than electrons. 
C) They both have the same speed. 
A) The electron because it has more mass. 
B) The photon because photons always travel through space faster than electrons. 
C) They both have the same speed.

Question 15

The work function of a certain metal is 1.90 eV.What is the longest wavelength of light that can cause photoelectron emission from this metal? (1 eV = 1.60 × 10-19 J,c = 3.00 × 108 m/s,h = 6.626 × 10-34 J ∙ s)

Accepted Answer

A) 231 nm 
B) 14.0 nm 
C) 62.4 nm 
D) 344 nm 
E) 654 nm 
A) 231 nm 
B) 14.0 nm 
C) 62.4 nm 
D) 344 nm 
E) 654 nm

Question 16

If the de Broglie wavelength of an electron is 2.4 μm,what is the speed of the electron?

Accepted Answer

A) 3.0 × 102 m/s 
B) 2.5 × 105 m/s 
C) 1.7 × 103 m/s 
D) 8.3 × 106 m/s 
A) 3.0 × 102 m/s 
B) 2.5 × 105 m/s 
C) 1.7 × 103 m/s 
D) 8.3 × 106 m/s

Question 17

What is the wavelength of the matter wave associated with a 0.50-kg ball moving at 25 m/s? (h = 6.626 × 10-34 J ∙ s)

Accepted Answer

A) 3.5 × 10-35 m 
B) 5.3 × 10-35 m 
C) 3.5 × 10-33 m 
D) 5.3 × 10-33 m 
A) 3.5 × 10-35 m 
B) 5.3 × 10-35 m 
C) 3.5 × 10-33 m 
D) 5.3 × 10-33 m

Question 18

An electron is accelerated from rest through a potential difference.After acceleration the electron has a wavelength of 880 nm.What is the potential difference responsible for the acceleration of the electron? (h = 6.626 × 10-34 J ∙ s,melectron = 9.11 × 10-31 kg,e = 1.6 10-19 C)

Accepted Answer

A) 1.9 × 10-6 V 
B) 1.7 × 10-6 V 
C) 2.2 × 10-6 V 
D) 2.5 × 10-6 V 
A) 1.9 × 10-6 V 
B) 1.7 × 10-6 V 
C) 2.2 × 10-6 V 
D) 2.5 × 10-6 V

Question 19

When the surface of a metal is exposed to blue light,electrons are emitted.If the intensity of the blue light is increased,which of the following things will also increase?

Accepted Answer

A) the number of electrons ejected per second 
B) the maximum kinetic energy of the ejected electrons 
C) the time lag between the onset of the absorption of light and the ejection of electrons 
D) the work function of the metal 
E) all of the above 
A) the number of electrons ejected per second 
B) the maximum kinetic energy of the ejected electrons 
C) the time lag between the onset of the absorption of light and the ejection of electrons 
D) the work function of the metal 
E) all of the above

Question 20

How much energy is carried by a photon of light having frequency 110 GHz? (h = 6.626 × 10-34 J ∙ s)

Accepted Answer

A) 1.1 × 10-20 J 
B) 1.4 × 10-22 J 
C) 7.3 × 10-23 J 
D) 1.3 × 10-25 J 
A) 1.1 × 10-20 J 
B) 1.4 × 10-22 J 
C) 7.3 × 10-23 J 
D) 1.3 × 10-25 J

Exam 30: Quantum Physics

What is the wavelength of the matter wave associated with an electron moving with a speed of 2.5 × 107 m/s? (melectron = 9.11 × 10-31 kg,h = 6.626 × 10-34 J ∙ s)

What is the de Broglie wavelength of a ball of mass 200 g moving at 30 m/s? (h = 6.626 × 10-34 J ∙ s)

A photocathode that has a work function of 2.4 eV is illuminated with monochromatic light having photon energy 3.5 eV.What is the wavelength of this light? (c = 3.00 × 108 m/s,h = 6.626 × 10-34 J ∙ s,1 eV = 1.60 × 10-19 J)

An electron has the same de Broglie wavelength as the wavelength of a 1.8 eV photon.What is the speed of the electron? (melectron = 9.11 × 10-31 kg,c = 3.00 × 108 m/s,1 eV = 1.60 × 10-19 J)

A blue laser beam is incident on a metallic surface,causing electrons to be ejected from the metal.If the frequency of the laser beam is increased while the intensity of the beam is held fixed,

What is the frequency of the most intense radiation from an object with temperature 100°C? The constant in Wien's law is 0.0029 m ∙ K.(c = 3.0 × 108 m/s)

Find the de Broglie wavelength of a 1.30-kg missile moving at (h = 6.626 × 10-34 J ∙ s)

If the de Broglie wavelength of an electron is 380 nm,what is the speed of this electron? (melectron = 9.11 × 10-31 kg,h = 6.626 × 10-34 J ∙ s)

When it is struck by 240-nm photons,a metal ejects electrons with a maximum kinetic energy of What is the work function of this material? (c = 3.00 × 108 m/s,h = 6.626 × 10-34 J ∙ s,1 eV = 16.0 × 10-19 J)

An electron is moving with the speed of 1780 m/s.What is its de Broglie wavelength? (melectron = 9.11 × 10-31 kg,h = 6.626 × 10-34 J ∙ s)

A beam of light falling on a metal surface is causing electrons to be ejected from the surface.If we now double the frequency of the light,which of the following statements are correct? (There could be more than one correct choice. )

Monochromatic light falls on a metal surface and electrons are ejected.If the intensity of the light is increased,what will happen to the ejection rate and maximum energy of the electrons?

If the wavelength of a photon in vacuum is the same as the de Broglie wavelength of an electron,which one is traveling faster through space?

The work function of a certain metal is 1.90 eV.What is the longest wavelength of light that can cause photoelectron emission from this metal? (1 eV = 1.60 × 10-19 J,c = 3.00 × 108 m/s,h = 6.626 × 10-34 J ∙ s)

If the de Broglie wavelength of an electron is 2.4 μm,what is the speed of the electron?

What is the wavelength of the matter wave associated with a 0.50-kg ball moving at 25 m/s? (h = 6.626 × 10-34 J ∙ s)

An electron is accelerated from rest through a potential difference.After acceleration the electron has a wavelength of 880 nm.What is the potential difference responsible for the acceleration of the electron? (h = 6.626 × 10-34 J ∙ s,melectron = 9.11 × 10-31 kg,e = 1.6 10-19 C)

When the surface of a metal is exposed to blue light,electrons are emitted.If the intensity of the blue light is increased,which of the following things will also increase?

How much energy is carried by a photon of light having frequency 110 GHz? (h = 6.626 × 10-34 J ∙ s)

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What is the wavelength of the matter wave associated with an electron moving with a speed of 2.5 × 10⁷ m/s? (m_electron = 9.11 × 10^-31 kg,h = 6.626 × 10^-34 J ∙ s)

What is the de Broglie wavelength of a ball of mass 200 g moving at 30 m/s? (h = 6.626 × 10^-34 J ∙ s)

A photocathode that has a work function of 2.4 eV is illuminated with monochromatic light having photon energy 3.5 eV.What is the wavelength of this light? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s,1 eV = 1.60 × 10^-19 J)

An electron has the same de Broglie wavelength as the wavelength of a 1.8 eV photon.What is the speed of the electron? (m_electron = 9.11 × 10^-31 kg,c = 3.00 × 10⁸ m/s,1 eV = 1.60 × 10^-19 J)

What is the frequency of the most intense radiation from an object with temperature 100°C? The constant in Wien's law is 0.0029 m ∙ K.(c = 3.0 × 10⁸ m/s)

Find the de Broglie wavelength of a 1.30-kg missile moving at (h = 6.626 × 10^-34 J ∙ s)

If the de Broglie wavelength of an electron is 380 nm,what is the speed of this electron? (m_electron = 9.11 × 10^-31 kg,h = 6.626 × 10^-34 J ∙ s)

When it is struck by 240-nm photons,a metal ejects electrons with a maximum kinetic energy of What is the work function of this material? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s,1 eV = 16.0 × 10^-19 J)

An electron is moving with the speed of 1780 m/s.What is its de Broglie wavelength? (m_electron = 9.11 × 10^-31 kg,h = 6.626 × 10^-34 J ∙ s)

The work function of a certain metal is 1.90 eV.What is the longest wavelength of light that can cause photoelectron emission from this metal? (1 eV = 1.60 × 10^-19 J,c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

What is the wavelength of the matter wave associated with a 0.50-kg ball moving at 25 m/s? (h = 6.626 × 10^-34 J ∙ s)

An electron is accelerated from rest through a potential difference.After acceleration the electron has a wavelength of 880 nm.What is the potential difference responsible for the acceleration of the electron? (h = 6.626 × 10^-34J ∙ s,m_electron = 9.11 × 10^-31 kg,e = 1.6 10^-19C)

How much energy is carried by a photon of light having frequency 110 GHz? (h = 6.626 × 10^-34 J ∙ s)