Deck 38: Photons: Light Waves Behaving As Particles

Question 1

A metal having a work function of 2.8 eV is illuminated with monochromatic light whose photon energy is 3.9 eV.What is the threshold frequency for photoelectron production? ,1 eV = 1.60 × 10^-19 J)

A) 6.8 × 10¹⁴ Hz
B) 2.7 × 10¹⁴ Hz
C) 7.6 × 10¹⁴ Hz
D) 8.5 × 10¹⁴ Hz
E) 9.4 × 10¹⁴ Hz

Answer 1

6.8 × 10¹⁴ Hz

Question 2

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 (h = 6.626 × 10^-34 J ∙ s,c = 3.00 × 10⁸ m/s)

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

Answer 2

1.0 × 10⁶

Question 3

In a photoelectric effect experiment,electrons emerge from a copper surface with a maximum kinetic energy of 1.10 eV when light shines on the surface.The work function of copper is 4.65 eV.Which one of the following values is closest to the wavelength of the light? ,c = 3.00 × 10⁸ m/s,1 eV = 1.60 × 10^-19 J)

A) 220 nm
B) 150 nm
C) 360 nm
D) 1100 nm

Answer 3

220 nm

Question 4

If the accuracy in measuring the position of a particle increases,the accuracy in measuring its velocity will

A) increase.
B) decrease.
C) remain the same.
D) It is impossible to say since the two measurements are independent and do not affect each other.

Question 5

A light beam from a 2.1-mW He-Ne laser has a wavelength of 633 nm.How many photons does the laser emit in one second? (h = 6.626 × 10^-34 J • s,c = 3.00 × 10⁸ m/s)

A) 6.7 × 10¹⁵
B) 8.8 × 10¹⁵
C) 1.1 × 10¹⁶
D) 1.3 × 10¹⁶

Question 6

A metal having a work function of 2.4 eV is illuminated with monochromatic light whose photon energy is 4.0 eV.What is the maximum kinetic energy of the photoelectrons produced by this light? (h = 6.626 × 10^-34 J • s,1 eV = 1.60 × 10^-19 J)

A) 2.6 × 10^-19 J
B) 3.8 × 10^-19 J
C) 4.7 × 10^-19 J
D) 5.5 × 10^-19 J
E) 6.4 × 10^-19 J

Question 7

A metal having a work function of 2.5 eV is illuminated with white light that has a continuous wavelength band from 400 nm to 700 nm.For which one of the following ranges of the wavelength band in this white light are photoelectrons NOT produced? , c = 3.00 × 10⁸ m/s,1 eV = 1.60 × 10^-19 J)

A) 500 nm to 700 nm
B) 400 nm to 560 nm
C) 500 nm to 560 nm
D) 400 nm to 500 nm
E) 560 nm to 700 nm

Question 8

Upon being struck by 240-nm photons,a metal ejects electrons with a maximum kinetic energy of What is the work function of this metal? (h = 6.626 × 10^-34 J • s, ,1 eV = 1.60 × 10^-19 J)

A) 3.73 eV
B) 3.13 eV
C) 4.33 eV
D) 4.92 eV

Question 9

A photon of initial wavelength 0.651 nm,after being scattered from a free electron at rest,moves off at an angle of 120° with respect to its incident direction. , , (a)What is the wavelength of the scattered photon?
(b)What is the energy of the scattered photon?

Question 10

A stopping potential of 0.50 V is required when a phototube is illuminated with monochromatic light of wavelength 590 nm.Monochromatic light of a different wavelength is now shown on the tube,and the stopping potential is measured to be 2.30 V.What is the wavelength of this new light? (c = 3.00 × 10⁸ m/s, , ,1 eV = 1.60 × 10^-19 J)

A) 320 nm
B) 300 nm
C) 340 nm
D) 360 nm
E) 410 nm

Question 11

When a certain metal is illuminated by light,photoelectrons are observed provided that the wavelength of the light is less than 669 nm.Which one of the following values is closest to the work function of this metal? (h = 6.626 × 10^-34 J • s,c = 3.00 × 10⁸ m/s,

A) 1.9 eV
B) 2.0 eV
C) 2.2 eV
D) 2.3 eV

Question 12

In a particular case of Compton scattering,a photon collides with a free electron and scatters backwards.The wavelength after the collision is exactly double the wavelength before the collision.What is the wavelength of the incident photon? (m_el = 9.11 × 10^-31 kg, ,c = 3.00 × 10⁸ m/s)

A) 3.6 pm
B) 4.8 pm
C) 2.4 pm
D) 1.2 pm
E) 6.0 pm

Question 13

A metal surface has a work function of 1.50 eV.Calculate the maximum kinetic energy,in eV,of electrons ejected from this surface by electromagnetic radiation of wavelength 311 nm. ,h = 6.626 × 10^-34 J • s,e = - 1.60 × 10^-19 C,1 eV = 1.60 × 10^-19 J)

Question 14

A beam of red light and a beam of violet light each deliver the same power on a surface.For which beam is the number of photons hitting the surface per second the greatest?

A) the red beam
B) the violet beam
C) It is the same for both beams.

Question 15

Light of wavelength 400 nm falls on a metal surface having a work function 1.70 eV.What is the maximum kinetic energy of the photoelectrons emitted from the metal? ,h = 6.626 × 10^-34 J • s = 4.141 × 10^-15 ev • s,1 eV = 1.60 × 10^-19 J)

A) 4.52 eV
B) 3.11 eV
C) 1.41 eV
D) 2.82 eV
E) 1.70 eV

Question 16

When a metal surface is illuminated with light of wavelength 437 nm,the stopping potential for photoelectrons is 1.67 V.(c = 3.00 × 10⁸ m/s, , ,
1 eV = 1.60 × 10^-19 J,m_el = 9.11 × 10^-31 kg)
(a)What is the work function of the metal,in eV?
(b)What is the maximum speed of the ejected electrons?

Question 17

If the accuracy in measuring the velocity of a particle increases,the accuracy in measuring its position will

A) increase.
B) decrease.
C) remain the same.
D) It is impossible to say since the two measurements are independent and do not affect each other.

Question 18

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 19

A laser emits light of wavelength 463 nm during a brief pulse that lasts for 25 ms and has a total energy of 1.2 J.How many photons are emitted in that single pulse? , h = 6.626 × 10^-34 J • s)

A) 2.8 × 10¹⁸
B) 6.9 × 10¹⁹
C) 3.4 × 10¹⁹
D) 1.1 × 10¹⁷
E) 2.2 × 10¹⁷

Question 20

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

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

Question 21

An unstable particle produced in a high-energy collision is measured to have an energy of 483 MeV and an uncertainty in energy of 84 keV.Use the Heisenberg uncertainty principle to estimate the lifetime of this particle.( h = 1.055 × 10^-34 J • s = 6.59 × 10^-16 eV • s)

Question 22

A nonrelativistic electron is confined to a length of 500 pm on the x-axis.What is the kinetic energy of the electron if its speed is equal to the minimum uncertainty possible in its speed? (h = 1.055 × 10^-34 J • s,m_el = 9.11 × 10^-31 kg,1 eV = 1.60 × 10^-19 J)

A) 0.00038 eV
B) 0.0038 eV
C) 0.038 eV
D) 0.38 eV
E) 3.8 eV

Question 23

A small dust particle of mass 7.90 × 10^-6 g is being observed under a magnifying lens.Its position is determined to within 0.0050 mm.(1 y = 3.156 × 10⁷ s, (a)Find the minimum uncertainty in its velocity implied by the uncertainty in its position.
(b)Assuming the dust particle is moving at the speed you just found,how many years would it take for the particle to move 1.0 mm?

Question 24

A laser produces a beam of 4000-nm light.A shutter allows a pulse of light,30 ps in duration,to pass.Which of the following is closest to the uncertainty in the energy of a photon in the pulse? ( h = 1.055 × 10^-34 J • s = 6.59 × 10^-16 eV • s)

A) 10^-6 eV
B) 10^-5 eV
C) 10^-4 eV
D) 10^-3 eV
E) 10^-2 eV

Question 25

A molecule of roughly spherical shape has a mass of 6.10 × 10^-25 kg and a diameter of 0.70 nm.The uncertainty in the measured position of the molecule is equal to the molecular diameter.What is the minimum uncertainty in the speed of this molecule?

A) 0.12 m/s
B) 1.2 m/s
C) 12 m/s
D) 0.012 m/s
E) 0.0012 m/s

Question 26

An ultraviolet source produces a monochromatic beam of 200-nm light.A shutter allows a pulse to pass that is 10,000 wavelengths long.The uncertainty in the energy of a photon in this pulse is closest to which of the following? ( h = 1.055 × 10^-34 J • s = 6.59 × 10^-16 eV • s,

A) 5 × 10^-7 eV
B) 5 × 10^-6 eV
C) 5 × 10^-5 eV
D) 5 × 10^-4 eV
E) 5 × 10^-3 eV

Question 27

The lifetime of an excited nuclear state is 1.0 ns.What is the minimum uncertainty in the energy of this state? ( h = 1.055 × 10^-34 J • s = 6.591 × 10^-16 eV • s,

A) 5.0 × 10^-10 eV
B) 5.0 × 10^-26 eV
C) 3.3 × 10^-25 eV
D) 1.6 × 10^-7 eV
E) 3.3 × 10^-7 eV

Question 28

A 440-nm spectral line is produced by a transition from an excited state to the ground state.The natural line width of the spectral line is 0.020 pm.The average time the atom spends in the excited state is closest to which of the following? ( h = 1.055 × 10^-34 J • s = 6.59 × 10^-16 eV • s)

A) 2.5 × 10^-6 s
B) 2.5 × 10^-7 s
C) 2.5 × 10^-8 s
D) 2.5 × 10^-9 s
E) 2.5 × 10^-10 s

Question 29

A beam of X-rays at a certain wavelength are scattered from a free electron at rest and the scattered beam is observed at 45.0° to the incident beam.What is the change in the wavelength of the X-rays? (m_el = 9.11 × 10^-31 kg,h = 6.626 × 10^-34 J • s,c = 3.00 × 10⁸ m/s)

A) 0.175 pm
B) 0.276 pm
C) 0.000 pm
D) 0.356 pm
E) 0.710 pm

Question 30

A measurement of an electron's speed is 2.0 × 10⁶ m/s and has an uncertainty of 10%.What is the minimum uncertainty in its position? ( h = 1.055 × 10^-34 J • s,m_el = 9.11 × 10^-31 kg)

A) 0.15 nm
B) 0.29 nm
C) 0.44 nm
D) 0.60 nm
E) 0.80 nm

Question 31

A nonrelativistic proton is confined to a length of 2.0 pm on the x-axis.What is the kinetic energy of the proton if its speed is equal to the minimum uncertainty possible in its speed? ,h = 1.055 × 10^-34 J • s,m_proton = 1.67 × 10^-27 kg)

A) 0.13 eV
B) 1.3 eV
C) 13 eV
D) 130 eV
E) 1300 eV

Question 32

X-rays of energy 2.9 × 10⁴ eV are scattered by a free stationary electron through an angle of 135°.What is the energy of the scattered X-rays,in electron volts? (m_el = 9.11 × 10^-31 kg, ,h = 6.626 × 10^-34 J • s,c = 3.00 × 10⁸ m/s,1 eV = 1.60 × 10^-19 J)

Question 33

A certain particle's energy is measured by a detector to within 1.0 × 10^-18.What is the minimum uncertainty we can have in its arrival time at the detector?

A) 5.3 × 10^-16 s
B) 5.3 × 10^-15 s
C) 5.3 × 10^-14 s
D) 5.3 × 10^-13 s
E) 5.3 × 10^-17 s

Question 34

An electron inside a hydrogen atom is confined to within a space of 0.110 nm.What is the minimum uncertainty in the electron's velocity? ( h = 1.055 × 10^-34 J • s,

A) 5.26 × 10⁵ m/s
B) 7.50 × 10⁵ m/s
C) 5.26 × 10⁷ m/s
D) 7.50 × 10⁷ m/s
E) 5.26 × 10⁹ m/s

Question 35

A photon of wavelength 18.0 pm is scattered through an angle of 120° by a stationary electron.What is the wavelength of the scattered photon? (m_el = 9.11 × 10^-31 kg, ,c = 3.00 × 10⁸ m/s)

A) 19.2 pm
B) 20.4 pm
C) 21.6 pm
D) 22.9 pm
E) 24.1 pm

Question 36

The excited state of a certain atom is 3.2 eV ± 0.21 eV. ,1 eV = 1.60 × 10^-19 J)
(a)What is the average lifetime of this state?
(b)If the excited energy were doubled to 6.4 eV ± 0.21 eV,how would the lifetime be affected?

Question 37

The energy of an electron state has an uncertainty of 0.500 eV.What is the minimum uncertainty in the lifetime of the level? ( h = 1.055 × 10^-34 J • s = 6.591 × 10^-16 eV • s,

A) 6.59 × 10^-16 s
B) 4.14 × 10^-15 s
C) 6.59 × 10^-12 s
D) 4.14 × 10^-11 s
E) 6.59 × 10^-9 s

Question 38

A photon of wavelength 29 pm is scattered by a stationary electron.What is the maximum possible energy loss of the photon? (m_el = 9.11 × 10^-31 kg,h = 6.626 × 10^-34 J • s,

A) 4.0 keV
B) 7.0 keV
C) 10 keV
D) 6.1 keV
E) 12 keV