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1 The “Cathode Rays” experiment is associated with: A Millikan
B Thomson
C TownsendD PlankE Compton
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2 The electron charge was measured the first time in:
A Cathode ray experimentB Photoelectric effect experimentC Oil drop experimentD Diffraction electrons from aluminum foilE Compton effect experiment
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3 Which of the following colors associated with the lowest temperature?
A VioletB BlueC GreenD YellowE Red
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4 Which of the following photons has the greatest energy?
A InfraredB BlueC XRayD γ photonE UV – photon
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5 The energy of a photon depends on:
A AmplitudeB SpeedC TemperatureD PressureE Frequency
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6 How does the energy of a photon change if the wavelength is doubled?
A DoublesB QuadruplesC Stays the sameD Is cut to onehalfE Is cut to onefourth
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7 How does the momentum of a photon change if the wavelength is halved?
A DoublesB QuadruplesC Stays the sameD Is cut to onehalfE Is cut to onefourth
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8 The photoelectric effect explains :
A The wave nature of lightB The particle nature of lightC The wave properties of an electronD The particle properties of an electronE The atomic structure
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9 The kinetic energy of photoelectrons depends on:
A Speed of lightB Angle of illuminationC Intensity of lightD WavelengthE None of the above
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10 Which of the following is the formula of the photon mass?
A m = h/cλB m = cλ/hC m = h/fD m = f/hE m = Ec2
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11 The maximum kinetic energy of photoelectrons depends on which of the following:
I. The light intensity II. The frequency of the light III. The nature of the photocell A Only IB Only IIC Only IIID Only I and IIE Only II and III
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12 Which of the following formulas explains the photoelectric effect?
A hλ = W0 + KEB hf = W0 KEC hf = W0 + KED hλ = W0 + KEE hc/λ = W0 KE
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13 Which of the following graphs is a correct relationship between the maximum kinetic energy of photoelectrons and the frequency of the incident light? A
B
C
D
E
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14 Which of the following graphs is a correct relationship between the maximum kinetic energy of photoelectrons and the intensity of the incident light?
A B
C D
E
I
I
I
I
I
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15 Which of the following graphs is a correct relationship between the de Broglie wavelength and the linear momentum of a particle? A B
C D
E
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16 All of the following are properties of γ rays EXCEPT:
A They discharge electrified objects B They ionize gases C They are deflected by magnetic fields D They penetrate light objects
E They are diffracted by crystals
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17 Which of the following phenomena provides the best evidence that light can have particle properties?
A Diffraction of light B Electromagnetic radiation C Compton effect D Electron diffraction
E γray diffraction
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18 Which of the following phenomena provides the best evidence that particles can have wave properties?
A The absorption of photons by electrons in an atom
B The alphadecay of radioactive nuclei
C The interference pattern produced by neutrons incident on a crystal
D The production of xrays by electrons striking a metal target
E The scattering of photons by electrons at rest
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19 Which of the following formulas can be used to determine the de Broglie wavelength?
A λ = hmvB λ = h/mvC λ = mv/hD λ = hm/cE λ = mc/h
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20 A photon can disappear producing an electron and positron, this phenomenon is called?
A Interference of lightB Diffraction of XRaysC Pair productionD Scattering of electronsE Annihilation
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21 When a positron collides with an electron they disappear producing photons, this phenomenon is called?
A Interference of lightB Diffraction of XRaysC Pair productionD Scattering of electronsE Annihilation
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22 The following statement: “In order to understand a given experiment, we must use either the wave or the photon theory, but not both” is called?
A Wave theory of lightB Particle theory of lightC Planetary theory of an atomD Principle of complementarityE Wave theory of matter
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23 Electrons are accelerated to a maximum speed of v in an XRay tube by an applied voltage V0. What is the maximum speed of the electrons if the voltage is quadrupled?
A 4v
B 2v
C
D
E v/4
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24 In a Compton Effect experiment a photon scattered from an electron at rest increases its wavelength from λi to λf. Which of the following deflecting angles gives the greatest raise in the wavelength of the scattered?
A 0 B 30 C 60 D 90 E 180
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25 Which one of the following objects moving at the same speed is associated with a greatest wavelength?
A NeutronB ElectronC Tennis ballD Bowling ballE α Particle
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26 According to the Bohr model of the atom, the angular momentum of an electron is:
A Linearly increases with increasing electron’s velocity
B Linearly increases with increasing orbital radiusC QuantizedD Inversely proportional to the electron’s velocityE Inversely proportional to the orbital radius
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27 Rutherford’s experiment “Scattering α–particles by a gold foil” was conducted to prove which of the following:
A Plumpudding model of the atomB Planetary model of the atomC De Broglie hypothesisD Wave nature of lightE Quantum theory of light
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28 In Rutherford’s Experiment “Scattering α – particles by a gold foil” the biggest part of α – particles could pass through the foil undeflected. Which of the following properties of the atom can be explained from this observation? A The positive charge is concentrated in the
nucleusB The nucleus has electrons and protonsC The atomic mass is concentrated in the nucleus
D The α – particles couldn’t be deflected by electrons
E The size of the nucleus is much less than the size of the atom
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29 Which of the following statement(s) can be associated with Bohr’s theory of the atom?
I. An electron orbiting the nucleus can change its energy continuously
II. An electron orbiting the nucleus emits energy and falls on the nucleus
III. An electron orbits the nucleus without radiating energy and can change its energy only by a certain portion when it jumps between the orbits
IV. The angular momentum of an electron around the nucleus is equal an integer times h/2π
A I and II
B II and IV
C II and III
D III and IVE I, II, III and IV
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30 When an electron falls from an orbit where n = 2 to n = 1:
A A photon is emittedB A photon is absorbedC No change in atomic energyD Atomic energy decreases to zeroE Atomic energy increases
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31 When an electron jumps from an orbit where n = 1 to n = 3 its orbital radius in terms of the smallest radius r1 is:
A r1/9B r1/3C 2 r1D 3 r1E 9 r1
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32 When an electron jumps from an orbit where n = 1 to n = 4 its energy in terms of the energy on the ground level is:
A E1/9B E1/16C 2 E1
D 4 E1
E 16 E1
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33 An electron is moving around a single proton in an orbit characterized by n = 5. How many of the electron's de Broglie wavelengths fit into the circumference of this orbit?
A 3B 4C 5D 16E 25
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34 In a cathode ray tube an electron is accelerated by an electric field. When the applied voltage is 600 V the electron’s De Broglie wavelength is λ. What is the De Broglie wavelength of the accelerated electron through a potential difference of 150 V?
A λB 2 λC λ /2D λ /4E 4 λ
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35 According to Maxwell’s theory of electromagnetism an electron orbiting the atomic nucleus:
A Changes its energy by certain portionsB Conserves its angular momentumC Conserves its energyD Radiates its energy and falls on the nucleus
E Changes its angular momentum by certain portions
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36 A hypothetical atom has the energy levels presented by the graph. An electron is excited from the ground state to the energy level 1 eV. The following are the energies of the emitted photons EXCEPT:
A 9 eVB 4 eVC 6 eVD 2 eVE 10 eV
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37 A hypothetical atom has energy levels presents by the graph. A container with the hypothetical gas is irradiated with electromagnetic radiation with the energy range from 4 eV to 9 eV. The following sequence of the photons can be found in the emission spectrum.
A 1 eV, 2 eV, and 6 eV onlyB 2 eV, 3 eV, and 4 eV onlyC 1 eV, 3 eV, and 5 eV onlyD 7 eV and 2 eV onlyE None from the above
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38 A hypothetical atom has energy levels presents by the graph. A container with the hypothetical gas is irradiated with electromagnetic radiation with the energy range from 4 eV to 9 eV. Which of the following transitions will produce a photon with the longest wavelength?
A From n = 4 to n = 1B From n = 4 to n = 2C From n = 2 to n = 1D From n = 3 to n = 1E From n = 4 to n = 3
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39 According to the Bohr’s theory of the hydrogen atom, electrons starting in the 4th energy level and eventually ending in the ground state could produce a total of how many lines in the hydrogen spectra?
A 6B 5C 7D 4E 3
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40 Which of the following transitions is related to the energy absorption?
A α1B α2C α3D α4E α5
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1. In an experiment conducted to investigate a photoelectric effect physics students use an apparatus show on the diagram. Photoelectrons emitted as a result of incident light can be accelerated or stopped by an applied voltage. When the incident light has a wavelength of 300 nm the stopping voltage required to stop them is 1 V. If the incident light has a wavelength of 200 nm the stopping voltage is 3 V.
a) Calculate the Plank’s constant from the data collected in the experiment.
hf = KE +φ
KE = hf-φ
1eV = (3x108 m/s/ 3x10-7m) h -φ3eV = (3x108 m/s / 2x107m) h φ
subtracting the 2 equations yields
2 eV = 0.5 x 1015 s-1 h
h = 4 x 10 -15eV-s
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1. In an experiment conducted to investigate a photoelectric effect physics students use an apparatus show on the diagram. Photoelectrons emitted as a result of incident light can be accelerated or stopped by an applied voltage. When the incident light has a wavelength of 300 nm the stopping voltage required to stop them is 1 V. If the incident light has a wavelength of 200 nm the stopping voltage is 3 V.
b) Calculate the work function for the photocell use in the experiment.
plug h into either of the equations from aand you get that φ = 3eV
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1. In an experiment conducted to investigate a photoelectric effect physics students use an apparatus show on the diagram. Photoelectrons emitted as a result of incident light can be accelerated or stopped by an applied voltage. When the incident light has a wavelength of 300 nm the stopping voltage required to stop them is 1 V. If the incident light has a wavelength of 200 nm the stopping voltage is 3 V.
c) Determine the threshold frequency for this type of photocell.
hf = 3 eV
f = 3 eV / 4x1015 eVs
f = 7.5 x 1014 Hz
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1. In an experiment conducted to investigate a photoelectric effect physics students use an apparatus show on the diagram. Photoelectrons emitted as a result of incident light can be accelerated or stopped by an applied voltage. When the incident light has a wavelength of 300 nm the stopping voltage required to stop them is 1 V. If the incident light has a wavelength of 200 nm the stopping voltage is 3 V.
d) Calculate the stopping voltage required to stop photoelectrons emitted by the cell when the incident light has a wavelength of 100 nm.
KE = 3x108 * 4 x1015/ 107 3 = 123 =9 eV
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2. A group of physics students conducts an experiment to investigate a photoelectric effect. They graphed the kinetic energy as a function of frequency of the incident light.
a) Determine the Plank’s constant from the given graph.
calculate the slope (1015 Hz, 1ev) and (1.5 x 1015Hz, 3eV)
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2. A group of physics students conducts an experiment to investigate a photoelectric effect. They graphed the kinetic energy as a function of frequency of the incident light.
b) Determine the work function of the photocell.
y intercept = 3
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2. A group of physics students conducts an experiment to investigate a photoelectric effect. They graphed the kinetic energy as a function of frequency of the incident light.
c) Determine the threshold frequency.
x intercept 0.75x1015 Hz
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2. A group of physics students conducts an experiment to investigate a photoelectric effect. They graphed the kinetic energy as a function of frequency of the incident light.
In the second trial students use a photocell with greater work function.
d) How does it change the graph? Explain.
slope remains the same (planck's constant) but y intercept will be at φ
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3. An electromagnetic radiation is incident on a metallic surface and electrons are emitted by the plate when the wavelength is 450 nm or less.
a. What is the work function of the metal?
hf = KE +φ
hf = φ
(3x108/4.5x10-7)x4x10-15 = 2.6667 V
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3. An electromagnetic radiation is incident on a metallic surface and electrons are emitted by the plate when the wavelength is 450 nm or less.
b. What is the maximum kinetic energy of photoelectrons if the incident light has a wavelength of 400 nm?
KE = hfφ = 4x10-15 3 x108 /4x10-7 -2.6667 =0.333eV
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3. An electromagnetic radiation is incident on a metallic surface and electrons are emitted by the plate when the wavelength is 450 nm or less.
c. What is the stopping voltage required to stop photoelectrons ejected by the plate when the incident light has a wavelength of 300 nm?
0.333V
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3. An electromagnetic radiation is incident on a metallic surface and electrons are emitted by the plate when the wavelength is 450 nm or less.
d. If the stopping voltage is 5 V, what is the wavelength of the incident light?
hf = KE + φ = 7.6667eV
λ = hc/7.6667 = 4x10-15 3x108 /7.6667 = 1.565x10-7m
157 nm
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4. An XRay photon with a wavelength of λi = 0.14 nm collides with a electron at rest and bounces back.
a. What is the wavelength of the scattered photon?
0.14nm + 6.6x1034/(9.11x1031 3x108)(1cos 180)= 0.145nm
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4. An XRay photon with a wavelength of λi = 0.14 nm collides with a electron at rest and bounces back.
b. What is the momentum of the recoil electron?
p = h/λ+h/λ'= 6.6x10-34(0.145x10-9 + 0.14x10-9)/(0.145x0.14x10-
18)= 9.3 x10 -24 kg-m/s
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4. An XRay photon with a wavelength of λi = 0.14 nm collides with a electron at rest and bounces back.
c. What is the energy of the recoil electron?
E = 1/2 p2/m = 1/2 (9.3x1024)2/(9.11x1031) = 4.7x1017J
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4. An XRay photon with a wavelength of λi = 0.14 nm collides with a electron at rest and bounces back.
d. Is the energy conserved during the collision?
yes
Eo =E'
Eo = hc/(0.14x10-9) = 1.46 x10-15 J
E' = hc/(0.145x10-9) + 1/2 p2/m = 1.41x10-15 +4.7 x10-17 =1.46 x10-15J
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4. An XRay photon with a wavelength of λi = 0.14 nm collides with a electron at rest and bounces back.
e. What is the De Broglie wave length of the scattered electron?
p = h/λ λ =h/p = 6.6x10-34/ 9.3x10-24 = 7.09x109 m
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5. An XRay tube accelerates an electron beam between two electrodes. A 70,000 V potential difference is applied across the tube.
a. What is the speed of the accelerated electrons?
v= √ (2Ue/m) =√ [2(1.6x10-19 70000/9.11x10-31)] = 1.6x108 m/s
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5. An XRay tube accelerates an electron beam between two electrodes. A 70,000 V potential difference is applied across the tube.
b. What is the energy of the emitted photons?
E= qV = 1.12x1014J = 70000eV
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5. An XRay tube accelerates an electron beam between two electrodes. A 70,000 V potential difference is applied across the tube.
c. What is the wavelength of the emitted photons?
λ = hc/E = 6.6x1034 x 3x108 / (1.12x1014) = 1.8x1011m
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5. An XRay tube accelerates an electron beam between two electrodes. A 70,000 V potential difference is applied across the tube.
d. What is the mass of the emitted photons?
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5. An XRay tube accelerates an electron beam between two electrodes. A 70,000 V potential difference is applied across the tube.
e. What is the momentum of the emitted photons?
p = me ve = 9.11x1031 x 1.6x108 = 1.5x1022kgm/s
p = h/λ = 6.6x10-34/1.8x10-11 = 3.67 x10-23kg-m/s
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6. A free electron is captured by a proton. As a result of this process two photons are emitted. The energy of the first photon is E1 = 3.4 eV.
a. Calculate the wavelength of the photon with energy E1.
λ = hc/E = 4.14x1015x3x108/(3.4)= 3.65x107m
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6. A free electron is captured by a proton. As a result of this process two photons are emitted. The energy of the first photon is E1 = 3.4 eV.
b. Calculate the energy of the second photon E2.
13.63.4 = 10.2eV
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6. A free electron is captured by a proton. As a result of this process two photons are emitted. The energy of the first photon is E1 = 3.4 eV.
c. Calculate the wavelength of the second photon?
1/3 of the other wavelength because E2 = 3E1
1.22x107 m
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6. A free electron is captured by a proton. As a result of this process two photons are emitted. The energy of the first photon is E1 = 3.4 eV.
d. On the diagram below show arrows associated with these transitions of the electron.
free to n=2
n=2 to n=1
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6. A free electron is captured by a proton. As a result of this process two photons are emitted. The energy of the first photon is E1 = 3.4 eV.
The electron stays on the ground level for a long period of time and then absorbs an energy of 15 eV from an incident photon.
e. What is the energy of the emitted electron?
1.4 eV
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6. A free electron is captured by a proton. As a result of this process two photons are emitted. The energy of the first photon is E1 = 3.4 eV.
f. What is the De Broglie wavelength of the emitted electron?
v = √(2 x1.4 x 1.6x10-19/(9.11x10-31)) = 7.0 x105m/s
λ = h/mv = 6.6x10-34/(9.11x10-31x7x105) = 1x10-9m
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