Question 1

The main purpose of a moderator in a nuclear reactor is to

Accepted Answer

A) absorb the neutrons and thereby decrease the reaction rate. 
B) absorb the neutrons and thereby increase the reaction rate. 
C) slow the neutrons and thereby decrease the reaction rate. 
D) slow the neutrons and thereby increase the reaction rate. 
E) cool the reactor chamber. 
A) absorb the neutrons and thereby decrease the reaction rate. 
B) absorb the neutrons and thereby increase the reaction rate. 
C) slow the neutrons and thereby decrease the reaction rate. 
D) slow the neutrons and thereby increase the reaction rate. 
E) cool the reactor chamber.

Question 2

What are the numbers of protons Z and neutrons N in the missing fragment of the following fission reaction?

Accepted Answer

A) Z = 55 and N = 37 
B) Z = 37 and N = 55 
C) Z = 92 and N = 37 
D) Z = 37 and N = 92 
E) Z = 37 and N = 58 
A) Z = 55 and N = 37 
B) Z = 37 and N = 55 
C) Z = 92 and N = 37 
D) Z = 37 and N = 92 
E) Z = 37 and N = 58

Question 3

Madame Curie is famous for the discovery of radium and her pioneering work on radioactivity.The half-life of radium (molar weight = 226g)is 1600 years.What is the activity (in Curie's)of 5.0g of radium?

Accepted Answer

A) 4.94 Ci 
B) 1.83 $\times$ 1011 Ci 
C) 0.512 Ci 
D) 52.3 Ci 
E) 3.59 $\times$ 1011 Ci 
A) 4.94 Ci 
B) 1.83 $\times$ 1011 Ci 
C) 0.512 Ci 
D) 52.3 Ci 
E) 3.59 $\times$ 1011 Ci

Question 4

A moderator is used to slow

Accepted Answer

A) protons 
B) alpha particles 
C) neutrons 
D) beta particles 
E) photons 
A) protons 
B) alpha particles 
C) neutrons 
D) beta particles 
E) photons

Question 5

The activity of a radioactive sample is defined as the number of decays per second.For a sample with N particles and a decay constant $\lambda$,the activity is

Accepted Answer

A) proportional to $\lambda$ and inversely proportional to N. 
B) proportional to $\lambda$ but independent of N. 
C) directly proportional to both $\lambda$ and N. 
D) independent of $\lambda$ but proportional to N. 
E) inversely proportional to both $\lambda$ and N. 
A) proportional to $\lambda$ and inversely proportional to N. 
B) proportional to $\lambda$ but independent of N. 
C) directly proportional to both $\lambda$ and N. 
D) independent of $\lambda$ but proportional to N. 
E) inversely proportional to both $\lambda$ and N.

Question 6

How many times larger is the radius of the nucleus 208Pb (Z=82)compared to the nucleus 40Ca (Z=20)?

Accepted Answer

A) 0.58 
B) 1.7 
C) 5.2 
D) 4.1 
E) 2.3 
A) 0.58 
B) 1.7 
C) 5.2 
D) 4.1 
E) 2.3

Question 7

Neutrons are effective particles for penetrating the nucleus because of their

Accepted Answer

A) small size. 
B) small mass. 
C) lack of charge. 
D) cheap production. 
E) easy control. 
A) small size. 
B) small mass. 
C) lack of charge. 
D) cheap production. 
E) easy control.

Question 8

The chemical characteristics of an atom (what element it is)are determined by

Accepted Answer

A) its atomic number. 
B) its mass number. 
C) its neutron number. 
D) its nucleon number. 
E) All of these are correct. 
A) its atomic number. 
B) its mass number. 
C) its neutron number. 
D) its nucleon number. 
E) All of these are correct.

Question 9

A barn is a unit of

Accepted Answer

A) momentum 
B) energy 
C) range 
D) cross section 
E) impact parameter 
A) momentum 
B) energy 
C) range 
D) cross section 
E) impact parameter

Question 10

A radioactive source has a half-life of 2 min.At time t = 0 it is placed near a detector and the counting rate is observed to be 3000 counts/s.If the detection efficiency is 25%,how many radioactive nuclei are there at time t = 2 min?

Accepted Answer

A) 1.04 $\times$ 106  
B) 1.67 $\times$ 106  
C) 2.08 $\times$ 106  
D) 3.41 $\times$ 106  
E) 3.79 $\times$ 106  
A) 1.04 $\times$ 106  
B) 1.67 $\times$ 106  
C) 2.08 $\times$ 106  
D) 3.41 $\times$ 106  
E) 3.79 $\times$ 106

Question 11

In an experimental inertial-confinement fusion reactor,inertial confinement has a useful duration of $\tau$ = 2.0 $\times$ 10-10 s.What must the density of the fusible material be in order to meet Lawson's criterion?

Accepted Answer

A) 2.0 $\times$ 1024 particles/cm3  
B) 5.0 $\times$ 1023 particles/cm3  
C) 6.0 $\times$ 1023 particles/cm3  
D) 2.5 $\times$ 1023 particles/cm3  
E) 7.0 $\times$ 1023 particles/cm3  
A) 2.0 $\times$ 1024 particles/cm3  
B) 5.0 $\times$ 1023 particles/cm3  
C) 6.0 $\times$ 1023 particles/cm3  
D) 2.5 $\times$ 1023 particles/cm3  
E) 7.0 $\times$ 1023 particles/cm3

Question 12

A flux of 1010 n/cm2 · s is incident on an   foil that is 0.10 cm thick.The density of aluminum is 2.7 g/cm3.The number of neutrons reacting with the aluminum is 104 n/cm2 · s.The cross section for this reaction is approximately

Accepted Answer

A) 10-6 m2  
B) 1.7 $\times$ 10-28 cm2  
C) 1 barn 
D) 6.6 $\times$ 10-32 m2  
E) 104 barn 
A) 10-6 m2  
B) 1.7 $\times$ 10-28 cm2  
C) 1 barn 
D) 6.6 $\times$ 10-32 m2  
E) 104 barn

Question 13

Assuming that 200 MeV of energy is released per fission,the mass of 235U that undergoes fission to operate a 250-MW reactor for 1 y is approximately

Accepted Answer

A) 100 kg 
B) 200 kg 
C) 400 kg 
D) 500 kg 
E) 1 Mg 
A) 100 kg 
B) 200 kg 
C) 400 kg 
D) 500 kg 
E) 1 Mg

Question 14

A nuclear explosion produces (among a lot of other things)7.9 $\times$1023 Bq of iodine-131,which has a half-life of 8.05 d,and 5.7 $\times$ 1021 Bq of barium-140,which has a half-life of 12.8 d.The total activity that remains after 145 d is

Accepted Answer

A) 3.5 $\times$ 1018 Bq 
B) 1.16 $\times$ 1020 Bq 
C) 2.2 $\times$ 1018 Bq 
D) 5.2 $\times$ 1018 Bq 
E) 7.3 $\times$ 1018 Bq 
A) 3.5 $\times$ 1018 Bq 
B) 1.16 $\times$ 1020 Bq 
C) 2.2 $\times$ 1018 Bq 
D) 5.2 $\times$ 1018 Bq 
E) 7.3 $\times$ 1018 Bq

Question 15

A radioactive source has a half-life of 2 min.At time t = 0 it is placed near a detector and the counting rate is observed to be 3000 counts/s.The counting rate at t = 10 min will be

Accepted Answer

A) 1500 counts/s 
B) 750 counts/s 
C) 375 counts/s 
D) 188 counts/s 
E) 94 counts/s 
A) 1500 counts/s 
B) 750 counts/s 
C) 375 counts/s 
D) 188 counts/s 
E) 94 counts/s

Question 16

The half-life of phosphorus-32 is 14.3 d.If you have 1.00 g of phosphorous-32 today,the amount remaining in 10 d will be approximately

Accepted Answer

A) 700 mg 
B) 650 mg 
C) 616 mg 
D) 384 mg 
E) 350 mg 
A) 700 mg 
B) 650 mg 
C) 616 mg 
D) 384 mg 
E) 350 mg

Question 17

The pair of nuclides that represents isotopes is

Accepted Answer

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

Question 18

The cross section of a nuclear reaction is

Accepted Answer

A) directly proportional to both the flux and the energy of the incident particle. 
B) independent of the incident particle but highly dependent on the target nuclei. 
C) dependent on the particular reaction being considered and the energy of the incident particle. 
D) influenced by the Coulomb force but is independent of the type of target nuclei and reaction. 
E) applicable only to neutron-induced reactions. 
A) directly proportional to both the flux and the energy of the incident particle. 
B) independent of the incident particle but highly dependent on the target nuclei. 
C) dependent on the particular reaction being considered and the energy of the incident particle. 
D) influenced by the Coulomb force but is independent of the type of target nuclei and reaction. 
E) applicable only to neutron-induced reactions.

Question 19

Many famous artifacts have been dated using 14C dating techniques.One of these were the Dead Sea Scrolls or manuscripts.An activity level of 0.20 Bq per gram of carbon was measured.If the half-life of 14C is 5730 years and there are about 15 decays per minute per gram of carbon in a living organism,then calculate the age of the famous manuscripts.

Accepted Answer

A) 2.7 $\times$ 103 years 
B) 1.9 $\times$ 103 years 
C) 1.3 $\times$ 103 years 
D) 3.7 $\times$ 104 years 
E) None of these is correct. 
A) 2.7 $\times$ 103 years 
B) 1.9 $\times$ 103 years 
C) 1.3 $\times$ 103 years 
D) 3.7 $\times$ 104 years 
E) None of these is correct.

Question 20

The fact that the binding energy per nucleon is roughly a constant over most of the range of stable nuclei indicates that the nuclear force is

Accepted Answer

A) short range. 
B) long range. 
C) weak. 
D) strong. 
E) repulsive. 
A) short range. 
B) long range. 
C) weak. 
D) strong. 
E) repulsive.

Exam 40: Nuclear Physics

The main purpose of a moderator in a nuclear reactor is to

What are the numbers of protons Z and neutrons N in the missing fragment of the following fission reaction?

Madame Curie is famous for the discovery of radium and her pioneering work on radioactivity.The half-life of radium (molar weight = 226g)is 1600 years.What is the activity (in Curie's)of 5.0g of radium?

A moderator is used to slow

The activity of a radioactive sample is defined as the number of decays per second.For a sample with N particles and a decay constant λ\lambdaλ ,the activity is

How many times larger is the radius of the nucleus 208Pb (Z=82)compared to the nucleus 40Ca (Z=20)?

Neutrons are effective particles for penetrating the nucleus because of their

The chemical characteristics of an atom (what element it is)are determined by

A barn is a unit of

A radioactive source has a half-life of 2 min.At time t = 0 it is placed near a detector and the counting rate is observed to be 3000 counts/s.If the detection efficiency is 25%,how many radioactive nuclei are there at time t = 2 min?

In an experimental inertial-confinement fusion reactor,inertial confinement has a useful duration of τ\tauτ = 2.0 ×\times× 10-10 s.What must the density of the fusible material be in order to meet Lawson's criterion?

A flux of 1010 n/cm2 · s is incident on an foil that is 0.10 cm thick.The density of aluminum is 2.7 g/cm3.The number of neutrons reacting with the aluminum is 104 n/cm2 · s.The cross section for this reaction is approximately

Assuming that 200 MeV of energy is released per fission,the mass of 235U that undergoes fission to operate a 250-MW reactor for 1 y is approximately

A nuclear explosion produces (among a lot of other things)7.9 ×\times× 1023 Bq of iodine-131,which has a half-life of 8.05 d,and 5.7 ×\times× 1021 Bq of barium-140,which has a half-life of 12.8 d.The total activity that remains after 145 d is

A radioactive source has a half-life of 2 min.At time t = 0 it is placed near a detector and the counting rate is observed to be 3000 counts/s.The counting rate at t = 10 min will be

The half-life of phosphorus-32 is 14.3 d.If you have 1.00 g of phosphorous-32 today,the amount remaining in 10 d will be approximately

The pair of nuclides that represents isotopes is

The cross section of a nuclear reaction is

The fact that the binding energy per nucleon is roughly a constant over most of the range of stable nuclei indicates that the nuclear force is

Systems of Measurement

Motion in One Dimension

Motion in Two and Three Dimensions

Newtons Laws

Applications of Newtons Laws

Work and Energy

Conservation of Energy

Systems of Particles and Conservation of Linear Momentum

Rotation

Conservation of Angular Momentum

Gravity

Static Equilibrium and Elasticity

Fluids

Oscillations

Wave Motion

Superposition and Standing Waves

Temperature and the Kinetic Theory of Gases

Heat and the First Law of Thermodynamics

The Second Law of Thermodynamics

Thermal Properties and Processes

The Electric Field I: Discrete Charge Distributions

The Electric Field Ii: Continuous Charge Distributions

Electric Potential

Capacitance

Electric Current and Direct-Current Circuits

The Magnetic Field

Sources of the Magnetic Field

Magnetic Induction

Alternating-Current Circuits

Maxwells Equations and Electromagnetic Waves

Properties of Light

Optical Images

Interference and Diffraction

Wave Particle Duality and Quantum Physics

Applications of the Schrodinger Equation

Atoms

Molecules

Solids and the Theory of Conduction

Relativity

Elementary Particles and the Beginning of the Universe

Filters

The activity of a radioactive sample is defined as the number of decays per second.For a sample with N particles and a decay constant $\lambda$ ,the activity is

How many times larger is the radius of the nucleus ²⁰⁸Pb (Z=82)compared to the nucleus ⁴⁰Ca (Z=20)?

In an experimental inertial-confinement fusion reactor,inertial confinement has a useful duration of $\tau$ = 2.0 $\times$ 10^-10 s.What must the density of the fusible material be in order to meet Lawson's criterion?

A flux of 10¹⁰ n/cm² · s is incident on an foil that is 0.10 cm thick.The density of aluminum is 2.7 g/cm³.The number of neutrons reacting with the aluminum is 10⁴ n/cm² · s.The cross section for this reaction is approximately

Assuming that 200 MeV of energy is released per fission,the mass of ²³⁵U that undergoes fission to operate a 250-MW reactor for 1 y is approximately

A nuclear explosion produces (among a lot of other things)7.9 $\times$ 10²³ Bq of iodine-131,which has a half-life of 8.05 d,and 5.7 $\times$ 10²¹ Bq of barium-140,which has a half-life of 12.8 d.The total activity that remains after 145 d is