Question 1

How many elementary fermions are known to exist in the universe (not including their anti-particles)?

Accepted Answer

A) 1 
B) 3 
C) 6 
D) 10 
E) 12 
A) 1 
B) 3 
C) 6 
D) 10 
E) 12

Question 2

What is the correct expression for the Planck time?

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 3

In a scattering experiment,an alpha particle initially with 8.00 MeV of kinetic energy can approach the nucleus of an unknown element to within 20.0 fm.If the only force between the alpha particle and the nucleus of the unknown element is the electric force,then what initial kinetic energy is required for a the alpha particle to approach within 30.0 fm of the nucleus?

Accepted Answer

A) 4.67 MeV 
B) 6.00 MeV 
C) 5.33 MeV 
D) 5.67 MeV 
A) 4.67 MeV 
B) 6.00 MeV 
C) 5.33 MeV 
D) 5.67 MeV

Question 4

If the energy of the virtual photon mediating an electron-proton scattering,e- + p $\rarr$e- + p,is 1.1 * 10-20 J,what is the range of this electromagnetic interaction?

Accepted Answer

A) 0.01 µm 
B) 3 µm 
C) 2 mm 
D) 1 cm 
A) 0.01 µm 
B) 3 µm 
C) 2 mm 
D) 1 cm

Question 5

What is the maximum wavelength of a photon that can produce a proton/anti-proton pair? The mass of a proton is 1.67 * 10-27kg.

Accepted Answer

A) 5.0 * 10-19 m 
B) 1.0 * 10-18 m 
C) 6.6 * 10-16 m 
D) 1.3 * 10-15 m 
E) There is no upper limit. 
A) 5.0 * 10-19 m 
B) 1.0 * 10-18 m 
C) 6.6 * 10-16 m 
D) 1.3 * 10-15 m 
E) There is no upper limit.

Question 6

The closest distance,rmin to a gold nucleus a 4.00 MeV alpha particle can get is

Accepted Answer

A) 16.2 fm. 
B) 24.7 fm. 
C) 32.4 fm. 
D) 44.5 fm. 
E) 56.9 fm. 
A) 16.2 fm. 
B) 24.7 fm. 
C) 32.4 fm. 
D) 44.5 fm. 
E) 56.9 fm.

Question 7

The decay of a neutron into a proton and electron (n $\rarr$ p + e-)is not allowed because of which one of the following conservation laws?

Accepted Answer

A) electric charge 
B) spin angular momentum 
C) energy 
D) lepton number 
E) Both B and D are correct. 
A) electric charge 
B) spin angular momentum 
C) energy 
D) lepton number 
E) Both B and D are correct.

Question 8

What is the correct expression for the Planck length?

Accepted Answer

A)    
B)    
C)    
D)    
A)    
B)    
C)    
D)

Question 9

An electron-positron pair traveling towards each other with a speed of v with respect to their center of mass,collide and annihilate according to e- + e+ $\rarr$ $\gamma$ + $\gamma$.An observer at rest with respect to the center of mass of the electron-positron pair,detects two photons each of wavelength 380 fm.What was the speed,v prior to the collision?

Accepted Answer

A) 0.976 c 
B) 0.923 c 
C) 0.950 c 
D) 0.995 c 
E) 0.988 c 
A) 0.976 c 
B) 0.923 c 
C) 0.950 c 
D) 0.995 c 
E) 0.988 c

Question 10

A 3.8-MeV proton is fired directly at a uranium nucleus (Z = 92).What is the closest that this proton can get to the uranium nucleus?

Accepted Answer

A) 2.7 * 10-15 m 
B) 9.3 * 10-15 m 
C) 1.2 * 10-14 m 
D) 3.5 * 10-14 m 
E) 4.6 * 10-14 m 
A) 2.7 * 10-15 m 
B) 9.3 * 10-15 m 
C) 1.2 * 10-14 m 
D) 3.5 * 10-14 m 
E) 4.6 * 10-14 m

Question 11

Which particle below has the largest mass?

Accepted Answer

A) neutral pi-meson (pion) 
B) neutral k-meson (kaon) 
C) proton 
D) neutron 
A) neutral pi-meson (pion) 
B) neutral k-meson (kaon) 
C) proton 
D) neutron

Question 12

An electron-positron pair traveling towards each other with a speed of 0.95 c with respect to their center of mass,collide and annihilate according to e- + e+ $\rarr$ $\gamma$ + $\gamma$.Assuming the observer is at rest with respect to the center of mass of the electron-positron pair,what is the wavelength of the photons?

Accepted Answer

A) 340 fm 
B) 380 fm 
C) 760 fm 
D) 1200 fm 
E) 2400 fm 
A) 340 fm 
B) 380 fm 
C) 760 fm 
D) 1200 fm 
E) 2400 fm

Question 13

An electron-positron pair traveling towards each other with a speed of v with respect to their center of mass,collide and annihilate according to e- + e+ $\rarr$ $\gamma$ + $\gamma$.An observer at rest with respect to the center of mass of the electron-positron pair,detects two photons each of frequency 5.13 * 1020 Hz .What was the speed,v prior to the collision?

Accepted Answer

A) 0.983 c 
B) 0.971 c 
C) 0.991 c 
D) 0.942 c 
E) 0.959 c 
A) 0.983 c 
B) 0.971 c 
C) 0.991 c 
D) 0.942 c 
E) 0.959 c

Question 14

Suppose a neutral rho meson (rest mass 770 MeV/c2)decays at rest into two oppositely charged pions (rest mass 139.5 MeV/c2).What is the momentum of each pion?

Accepted Answer

A) 305 MeV/c 
B) 196 MeV/c 
C) 359 MeV/c 
D) 402 MeV/c 
A) 305 MeV/c 
B) 196 MeV/c 
C) 359 MeV/c 
D) 402 MeV/c

Question 15

Compared to the elementary charge,Planck charge is about 12 times larger.

Accepted Answer

A) False 
B) True 
A) False 
B) True

Question 16

The W bosons,having a mass of 80.403 GeV/c2 are elementary bosons for the electroweak interaction.The order of magnitude of the range of the corresponding weak interaction is

Accepted Answer

A) 10-16 m. 
B) 10-17 m. 
C) 10-18 m. 
D) 10-19 m. 
E) 10-20 m. 
A) 10-16 m. 
B) 10-17 m. 
C) 10-18 m. 
D) 10-19 m. 
E) 10-20 m.

Question 17

Protons with kinetic energy of 1.6 MeV scatter off a lead (Pb)nuclei in a foil target.Each Pb nucleus contains 82 protons.If both the incoming protons and the Pb nuclei can be treated as point objects and the differential scattering cross section for the protons to scatter off the Pb nuclei is 3.2 * 10-27 m2/sr,what is the scattering angle relative to their initial velocity?

Accepted Answer

A) 57S1U1P1$\circ$S1S1P0 
B) 35S1U1P1$\circ$S1S1P0 
C) 50S1U1P1$\circ$S1S1P0 
D) 70S1U1P1$\circ$S1S1P0 
E) 25S1U1P1$\circ$S1S1P0 
A) 57S1U1P1$\circ$S1S1P0 
B) 35S1U1P1$\circ$S1S1P0 
C) 50S1U1P1$\circ$S1S1P0 
D) 70S1U1P1$\circ$S1S1P0 
E) 25S1U1P1$\circ$S1S1P0

Question 18

Determine the approximate probing distance of a photon with a minimum energy of 4.0 keV.

Accepted Answer

A) 1.3 * 104 fm 
B) 3.7 * 104 fm 
C) 4.9 * 104 fm 
D) 5.1 * 104 fm 
E) 1.3 * 109 fm 
A) 1.3 * 104 fm 
B) 3.7 * 104 fm 
C) 4.9 * 104 fm 
D) 5.1 * 104 fm 
E) 1.3 * 109 fm

Question 19

A proton and an antiproton at rest annihilate to create two gamma photons.The wavelength of the photons is

Accepted Answer

A) 5.91 fm. 
B) 3.24 fm. 
C) 1.32 fm. 
D) 0.78 fm. 
A) 5.91 fm. 
B) 3.24 fm. 
C) 1.32 fm. 
D) 0.78 fm.

Exam 39: Elementary Particle Physics

How many elementary fermions are known to exist in the universe (not including their anti-particles)?

What is the correct expression for the Planck time?

If the energy of the virtual photon mediating an electron-proton scattering,e- + p →\rarr→ e- + p,is 1.1 * 10-20 J,what is the range of this electromagnetic interaction?

What is the maximum wavelength of a photon that can produce a proton/anti-proton pair? The mass of a proton is 1.67 * 10-27kg.

The closest distance,rmin to a gold nucleus a 4.00 MeV alpha particle can get is

The decay of a neutron into a proton and electron (n →\rarr→ p + e-)is not allowed because of which one of the following conservation laws?

What is the correct expression for the Planck length?

A 3.8-MeV proton is fired directly at a uranium nucleus (Z = 92).What is the closest that this proton can get to the uranium nucleus?

Which particle below has the largest mass?

Suppose a neutral rho meson (rest mass 770 MeV/c2)decays at rest into two oppositely charged pions (rest mass 139.5 MeV/c2).What is the momentum of each pion?

Compared to the elementary charge,Planck charge is about 12 times larger.

The W bosons,having a mass of 80.403 GeV/c2 are elementary bosons for the electroweak interaction.The order of magnitude of the range of the corresponding weak interaction is

Determine the approximate probing distance of a photon with a minimum energy of 4.0 keV.

A proton and an antiproton at rest annihilate to create two gamma photons.The wavelength of the photons is

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If the energy of the virtual photon mediating an electron-proton scattering,e^- + p $\rarr$ e^- + p,is 1.1 * 10^-20 J,what is the range of this electromagnetic interaction?

What is the maximum wavelength of a photon that can produce a proton/anti-proton pair? The mass of a proton is 1.67 * 10^-27kg.

The closest distance,r_min to a gold nucleus a 4.00 MeV alpha particle can get is

The decay of a neutron into a proton and electron (n $\rarr$ p + e^-)is not allowed because of which one of the following conservation laws?

Suppose a neutral rho meson (rest mass 770 MeV/c²)decays at rest into two oppositely charged pions (rest mass 139.5 MeV/c²).What is the momentum of each pion?

The W bosons,having a mass of 80.403 GeV/c² are elementary bosons for the electroweak interaction.The order of magnitude of the range of the corresponding weak interaction is