Deck 27: Quantum Optics

Question 1

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.)

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.

Answer 1

E

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?

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

Answer 2

A

Question 3

Two identical metal bars are heated up until they are both glowing.One of them is "red hot" and the other is "blue hot." Which one is hotter,the one that glows red or the one that glows blue?

A)the red one
B)the blue one
C)We cannot tell without knowing more about the two bars.

Answer 3

B

Question 4

An object having a fixed emissivity of 0.725 radiates heat at a rate of 10 W when it is at an absolute temperature T.If its temperature is doubled to 2T,at what rate will it now radiate?

A)20 W
B)40 W
C)80 W
D)160 W
E)320 W

Question 5

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

A)the number of photons per second traveling in the beam.
B)the energy of each photon.
C)the speed of the photons.
D)the frequency of the light.
E)the wavelength of the photons.

Question 6

Two sources emit beams of microwaves.The microwaves from source A have a frequency of 10 GHz,and the ones from source B have a frequency of 20 GHz.This is all we know about the two beams.Which of the following statements about these beams are correct? (There could be more than one correct choice.)

A)Beam B carries twice as many photons per second as beam A.
B)A photon in beam B has twice the energy of a photon in beam A.
C)The intensity of beam B is twice as great as the intensity of beam A.
D)A photon in beam B has the same energy as a photon in beam A.
E)None of the above statements are true.

Question 7

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,

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 8

Two sources emit beams of light of wavelength 550 nm.The light from source A has an intensity of 10 µW/m²,and the light from source B has an intensity of 20 µW/m².This is all we know about the two beams.Which of the following statements about these beams are correct? (There could be more than one correct choice.)

A)Beam B carries twice as many photons per second as beam A.
B)A photon in beam B has twice the energy of a photon in beam A.
C)The frequency of the light in beam B is twice as great as the frequency of the light in beam A.
D)A photon in beam B has the same energy as a photon in beam A.
E)None of the above statements are true.

Question 9

If the absolute temperature of an object is tripled,the thermal power radiated by this object (assuming that its emissivity and size are not affected by the temperature change)will

A)increase by a factor of 3.
B)increase by a factor of 9.
C)increase by a factor of 18.
D)increase by a factor of 27.
E)increase by a factor of 81.

Question 10

Photon A has twice the momentum of photon B as both of them are traveling in vacuum.Which statements about these photons are correct? (There could be more than one correct choice.)

A)Photon A is traveling twice as fast as photon B.
B)Both photons have the same speed.
C)Both photons have the same wavelength.
D)The wavelength of photon A is twice as great as the wavelength of photon B.
E)The wavelength of photon B is twice as great as the wavelength of photon A.

Question 11

A photon scatters off of a stationary electron.Which of the following statements about the photon are true? (There could be more than one correct choice.)

A)Its wavelength increases due to the scattering.
B)Its frequency increases due to the scattering.
C)Its wavelength decreases due to the scattering.
D)Its frequency decreases due to the scattering.
E)Its energy does not change.

Question 12

If you double the frequency of the light in a laser beam,but keep the number of photons per second in the beam fixed,which of the following statements are correct? (There could be more than one correct choice.)

A)The power in the beam does not change.
B)The intensity of the beam doubles.
C)The energy of individual photons does not change.
D)The energy of individual photons doubles.
E)The wavelength of the individual photons doubles.

Question 13

As the temperature of a blackbody increases,what happens to the peak wavelength of the light it radiates?

A)It gets longer.
B)It gets shorter.
C)The wavelength is not affected by the temperature of the object.

Question 14

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?

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 15

By what primary heat transfer mechanism does the sun warm the earth?

A)convection
B)conduction
C)radiation
D)All of the above processes are equally important in combination.

Question 16

Which of the following actions will increase the energy of a photon? (There could be more than one correct choice.)

A)Increase its wavelength.
B)Increase its frequency.
C)Decrease its wavelength.
D)Decrease its frequency.
E)Increase its speed.

Question 17

A photon of blue light and a photon of red light are traveling in vacuum.The photon of blue light

A)has a smaller wavelength than a photon of red light and travels with the same speed.
B)has a smaller wavelength than a photon of red light and travels with a greater speed.
C)has a longer wavelength than a photon of red light and travels with the same speed.
D)has a longer wavelength than a photon of red light and travels with a greater speed.

Question 18

Light of a given wavelength is used to illuminate the surface of a metal,however,no photoelectrons are emitted.In order to cause electrons to be ejected from the surface of this metal you should

A)use light of a longer wavelength.
B)use light of a shorter wavelength.
C)use light of the same wavelength but increase its intensity.
D)use light of the same wavelength but decrease its intensity.

Question 19

If the wavelength of a photon is doubled,what happens to its energy?

A)It is reduced to one-half of its original value.
B)It stays the same.
C)It is doubled.
D)It is increased to four times its original value.
E)It is reduced to one-fourth of its original value.

Question 20

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?

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 21

In an electric furnace used for refining steel,the temperature is monitored by measuring the radiant power emitted through a small hole in the wall of the furnace,of area 0.5 cm².This hole acts like a perfect blackbody radiator having the same temperature as the interior of the furnace.If the temperature of the furnace (and therefore of the hole)is to be maintained at 1650°C,how much power will the hole radiate?

A)20 W
B)30 W
C)40 W
D)50 W

Question 22

A sphere of surface area 1.25 m² and emissivity 1.0 is at a temperature of 100°C.At what rate does it radiate energy into empty space? (σ = 5.67 × 10^-8 W/m² ∙ K⁴)

A)7.1 W
B)0.71 mW
C)1.4 kW
D)9.9 mW
E)3.7 W

Question 23

If the surface of our bodies is at 37°C,at what wavelength does the radiation that we emit peak if we behave like a blackbody? The constant in Wien's law is 0.0029 m ∙ K.

Question 24

The cosmic background radiation permeating the universe has the spectrum of a 2.7-K blackbody radiator.What is the peak wavelength of this radiation? The constant in Wien's law is 0.0029 m ∙ K.

Question 25

If the sunlight from a star peaks at a wavelength of 0.55 µm,what temperature does this imply for the surface of that star? The constant in Wien's law is 0.00290 m ∙ K.

A)9500 K
B)5300 K
C)2500 K
D)25,000 K
E)15,000 K

Question 26

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)

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

Question 27

A giant star radiates energy at the rate of 3.0 × 10³⁰ W,and its surface temperature has been measured to be 3000 K.Assuming that it is a perfect emitter,what is the radius of this star?(σ = 5.67 × 10^-8 W/m² ∙ K⁴)

A)7.8 × 10¹⁰ m
B)8.7 × 10¹⁰ m
C)1.4 × 10¹⁰ m
D)1.9 × 10¹¹ m
E)2.3 × 10¹¹ m

Question 28

What is the surface temperature of a star,if its radiation peak occurs at a frequency of 1.06 × 10¹⁵ Hz? (c = 3.00 × 10⁸ m/s,and the constant in Wien's law is 0.00290 m ∙ K)

A)17,000 K
B)14,500 K
C)19,000 K
D)20,400 K
E)10,200 K

Question 29

The cylindrical filament in a light bulb has a diameter of 0.050 mm,an emissivity of 1.0,and a temperature of 3000°C.How long should the filament be in order to radiate 60 W of power? (σ = 5.67 × 10^-8 W/m² ∙ K⁴)

A)11 cm
B)9.4 cm
C)8.6 cm
D)7.2 cm
E)5.9 cm

Question 30

If the frequency of a light beam is doubled,what happens to the momentum of the photons in that beam of light?

A)It stays the same.
B)It is halved.
C)It is doubled.
D)It is reduced to one-fourth of its original value.
E)It is increased to four times its original value.

Question 31

An x-ray tube accelerates electrons through a potential difference of 50.0 kV.If an electron in the beam suddenly give up its kinetic energy in a collision,what is the shortest wavelength x-ray it could produce? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s,e = 1.60 × 10^-19
C)

Question 32

What are the wavelength and the corresponding photon energy (in electron-volts)of the primary light emitted by an ideal blackbody at each of the following temperatures? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s,1 eV = 1.60 × 10^-19 J,and the constant in Wein's law is 0.00290 m ∙ K)
(a)400°C?
(b)800°C?
(c)1200°C?

Question 33

A blacksmith is flattening a steel plate having dimensions 10 cm × 15 cm × 1 mm.He has heated the plate to 900 K.If the emissivity of the plate is 0.75,at what rate does it lose energy by radiation? Ignore any heat exchange with the surroundings.(σ = 5.67 × 10^-8 W/m² ∙ K⁴)

A)360 W
B)760 W
C)790 W
D)850 W
E)880 W

Question 34

At what rate are photons emitted by a 50.0-W sodium vapor lamp if it is producing monochromatic light of wavelength 589 nm? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

Question 35

If the wavelength of a photon is the same as the de Broglie wavelength of an electron,which one has the greater momentum?

A)The electron because it has more mass.
B)The photon because it is traveling faster.
C)They both have the same momentum.

Question 36

The surface temperature of the star is 6000 K.At what wavelength is its light output a maximum? The constant in Wien's law is 0.00290 m ∙ K.

A)850 nm
B)907 nm
C)311 nm
D)483 nm
E)502 nm

Question 37

What is the wavelength of the most intense light emitted by a giant star of surface temperature 5000 K? The constant in Wien's law is 0.00290 m ∙ K.

A)576 nm
B)578 nm
C)580 nm
D)582 nm

Question 38

How much power does a sphere with a radius of 10 cm radiate into empty space if is has an emissivity of 1.0 and is kept at a temperature of 400 K? (σ = 5.67 × 10^-8 W/m² ∙ K⁴)

A)60 W
B)70 W
C)180 W
D)210 W
E)360 W

Question 39

If the wavelength of a light beam is doubled,what happens to the momentum of the photons in that light beam?

A)It is halved.
B)It stays the same.
C)It is doubled.
D)It is reduced by one-fourth of its original value.
E)It is increased to four times its original value.

Question 40

The radius of a star is 6.95 × 10⁸ m,and its rate of radiation has been measured to be 5.32 × 10²⁶ W.Assuming that it is a perfect emitter,what is the temperature of the surface of this star? (σ = 5.67 × 10^-8 W/m² ∙ K⁴)

A)6.27 × 10³ K
B)8.25 × 10³ K
C)8.87 × 10³ K
D)3.93 × 10⁷ K
E)5.78 × 10⁷ K

Question 41

A small gas laser of the type used in classrooms may radiate light at a power level of 2.0 mW.If the wavelength of the laser light is 642 nm,how many photons does it emit per second? (c = 3.0 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

Question 42

Gamma rays are photons with very high energy.How many visible-light photons with a wavelength of 500 nm would you need to equal the energy of a gamma-ray photon with energy

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

Question 43

What is the photon energy of red light having a wavelength of 6.40 × 10² nm? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

A)1.13 × 10^-19 J
B)1.31 × 10^-19 J
C)3.11 × 10^-19 J
D)1.94 × 10^-19 J

Question 44

An 84-kW AM radio station broadcasts at 1000 kHz.How many photons are emitted each second by the transmitting antenna? (h = 6.626 × 10^-34 J ∙ s)

A)1.3 ×
B)2.9 ×
C)6.3 ×
D)1.4 ×

Question 45

If the longest wavelength of light that is able to dislodge electrons from a metal is 373 nm,what is the work function of that metal,in electron-volts? (1 eV = 1.60 × 10^-19 J,c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

Question 46

A metal surface has a work function of 2.50 eV.What is the longest wavelength of light that will eject electrons from the surface of this metal? (1 eV = 1.60 × 10^-19 J,c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

Question 47

The human eye can just detect green light of wavelength 500 nm if it arrives at the retina at the rate of 2 × 10^-18 W.How many photons arrive each second? (c = 3.0 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

Question 48

A laser emits a pulse of light that lasts 10 ns.The light has a wavelength of 690 nm,and each pulse has an energy of 480 mJ.How many photons are emitted in each pulse? (c = 3.0 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

A)1.7 × 10¹⁸
B)2.1 ×
C)2.6 ×
D)3.1 ×

Question 49

A helium-neon laser emits light at 632.8 nm.If the laser emits photons/second,what is its power output in mW? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

A)57.2 mW
B)28.6 mW
C)37.2 mW
D)45.7 mW

Question 50

What is the energy (in eV)of an optical photon of frequency (h = 6.626 × 10^-34 J ∙ s,1 eV = 1.60 × 10^-19 J)

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

Question 51

A photoelectric surface has a work function of 2.10 eV.Calculate the maximum kinetic energy,in eV,of electrons ejected from this surface by electromagnetic radiation of wavelength 356 nm.(1 eV = 1.60 × 10^-19 J,c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

Question 52

What frequency of electromagnetic radiation has photons of energy 4.7 × 10^-25 J? (h = 6.626 × 10^-34 J ∙ s)

A)710 kHz
B)4.7 MHz
C)710 MHz
D)1.4 GHz

Question 53

Each photon in a beam of light has an energy of 4.20 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)

A)321 nm
B)103 nm
C)296 nm
D)412 nm
E)420 nm

Question 54

What is the wavelength of a photon having energy 2.00 eV? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s,1 eV = 1.60 × 10^-19 J)

Question 55

A metallic surface is illuminated with light of wavelength 400 nm.If the work function for this metal is 2.40 eV,what is the maximum kinetic energy of the ejected electrons,in electron-volts? (1 eV = 1.60 × 10^-19 J,c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

Question 56

Gamma rays are photons with very high energy.What is the wavelength of a gamma-ray photon with energy 7.7 × 10^-13 J? (c = 3.0 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

A)2.6 × 10^-13 m
B)3.9 × 10^-13 m
C)3.1 × 10^-13 m
D)3.5 × 10^-13 m

Question 57

What is the wavelength of a 6.32-eV photon? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s,1 eV = 1.60 × 10^-19 J)

A)197 nm
B)167 nm
C)216 nm
D)234 nm

Question 58

A laser pulse of duration 25 ms has a total energy of 1.4 J.If the wavelength of this radiation is 567 nm,how many photons are emitted in one pulse? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

A)4.0 × 10¹⁸
B)9.9 × 10¹⁹
C)4.8 × 10¹⁹
D)1.6 × 10¹⁷
E)3.2 × 10¹⁷

Question 59

For what wavelength does a 100-mW laser beam deliver 1.6 × 10¹⁷ photons in one second? (c = 3.0 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

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

Question 60

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

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

Question 61

What is the cutoff (threshold)frequency for a metal surface that has a work function of 5.42 eV? (1 eV = 1.60 × 10^-19 J,h = 6.626 × 10^-34 J ∙ s)

A)1.31 × Hz
B)2.01 × Hz
C)3.01 × Hz
D)5.02 × Hz
E)6.04 × Hz

Question 62

What is the longest wavelength of electromagnetic radiation that will eject photoelectrons from sodium metal for which the work function is 2.28 eV? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J)

A)580 nm
B)499 nm
C)633 nm
D)668 nm
E)545 nm

Question 63

When it is struck by 240-nm photons,a material having a work function of 2.60 eV emits electrons.What is the maximum kinetic energy of the emitted electrons? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s,1 eV = 1.60 × 10^-19 J)

A)2.58 eV
B)5.18 eV
C)2.00 eV
D)4.21 eV

Question 64

What is the longest wavelength of light that can cause photoelectron emission from a metal that has a work function of 2.20 eV? (1 eV = 1.60 × 10^-19 J,c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

A)417 nm
B)257 nm
C)344 nm
D)565 nm
E)610 nm

Question 65

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)

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

Question 66

A photocathode having a work function of 2.4 eV is illuminated with monochromatic light whose photon energy is 3.4 eV.What is maximum kinetic energy of the photoelectrons produced?(c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s,1 eV = 1.60 × 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 67

When a metal is illuminated by light,photoelectrons are observed provided that the wavelength of the light is less than 520 nm.What is the metal's work function? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s,1 eV = 1.60 × 10^-19 J)

A)2.4 eV
B)2.6 eV
C)2.8 eV
D)3.0 eV

Question 68

A metal has a work function of 4.50 eV.Find the maximum kinetic energy of the photoelectrons if light of wavelength 250 nm shines on the metal.(1 eV = 1.60 × 10^-19 J,c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

A)0.00 eV
B)0.37 eV
C)0.47 eV
D)0.53 eV

Question 69

In her physics laboratory,Mathilda shines electromagnetic radiation on a material and collects photoelectric data to determine Planck's constant.She measures a stopping potential of 5.82 V for radiation of wavelength 100 nm,and 17.99 V for radiation of wavelength 50.0 nm.(1 eV = 1.60 × 10^-19 J,c = 3.00 × 10⁸ m/s)
(a)Using Mathilda's data,what value does she determine for Planck's constant?
(b)What is the work function of the material Mathilda is using,in electron-volts?

Question 70

When a photoelectric surface is illuminated with light of wavelength 437 nm,the stopping potential is measured to be 1.67 V.(1 eV = 1.60 × 10^-19 J,e = 1.60 × 10^-19 C,m_electron = 9.11 × 10^-31 kg,h = 6.626 × 10^-34 J ∙ s)
(a)What is the work function of the metal,in eV?
(b)What is the maximum speed of the ejected electrons?

Question 71

Light with a frequency of 8.70 × 10¹⁴ Hz is incident on a metal that has a work function of 2.80 eV.What is the maximum kinetic energy that a photoelectron ejected in this process can have? (1 eV = 1.60 × 10^-19 J,h = 6.626 × 10^-34 J ∙ s)

A)8.7 × 10^-19 J
B)3.1 × 10^-19 J
C)1.3 × 10^-19 J
D)2.4 × 10^-19 J
E)4.5 × 10^-19 J

Question 72

Light with a wavelength of 310 nm is incident on a metal that has a work function of 3.80 eV.What is the maximum kinetic energy that a photoelectron ejected in this process can have? (1 eV = 1.60 × 10^-19 J,c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

A)0.62 × 10^-19 J
B)0.21 × 10^-19 J
C)0.36 × 10^-19 J
D)0.48 × 10^-19 J
E)0.33 × 10^-19 J

Question 73

If the work function of a metal surface is 2.20 eV,what frequency of incident light would give a maximum kinetic energy of 0.25 eV to the photoelectrons ejected from this surface? (1 eV = 1.60 × 10^-19 J, h = 6.626 × 10^-34 J ∙ s)

A)2.05 × 10¹⁴ Hz
B)1.02 × 10¹⁴ Hz
C)2.50 × 10¹⁴ Hz
D)3.53 × 10¹⁴ Hz
E)5.92 × 10¹⁴ Hz

Question 74

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.What is the range of the wavelength band in this white light illumination for which photoelectrons are not produced?(c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s,1 eV = 1.60 × 10^-19 J)

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

Question 75

For a certain metal,light of frequency 7.24 × 10^-14 Hz is just barely able to dislodge photoelectrons from the metal.(h = 6.626 × 10^-34 J ∙ s, 1 eV = 1.60 × 10^-19 J,e = 1.60 × 10^-19
C)
(a)What will be the stopping potential if light of frequency 8.75 × 10^-14 Hz is shone on the metal?
(b)What is the work function (in electron-volts)of this metal?

Question 76

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)

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

Question 77

The work function of a particular metal is What is the photoelectric cutoff (threshold)wavelength for this metal? (c = 3.00 × 10⁸ m/s,h = 6.626 × 10^-34 J ∙ s)

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

Question 78

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)

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

Question 79

A photocathode having a work function of 2.8 eV is illuminated with monochromatic electromagnetic radiation whose photon energy is 4.0 eV.What is the threshold (cutoff)frequency for photoelectron production? (1 eV = 1.60 × 10^-19 J,h = 6.626 × 10^-34 J ∙ s)

A)6.8 × 10¹⁴ _Hz
B)2.9 × 10¹⁴ _Hz
C)7.7 × 10¹⁴ _Hz
D)8.6 × 10¹⁴ _Hz
E)9.7 × 10¹⁴ _Hz

Question 80

A beam of light with a frequency range from 3.01 × 10¹⁴ Hz to 6.10 × 10¹⁴ Hz is incident on a metal surface.If the work function of the metal surface is 2.20 eV,what is the maximum kinetic energy of photoelectrons ejected from this surface? (h = 6.626 × 10^-34 J ∙ s,1 eV = 1.60 × 10^-19 J)

A)0.33 eV
B)0.21 eV
C)0.42 eV
D)0.16 eV
E)0.48 eV