Physics · Science General

Nuclear Physics and Energy

1,296 Questions

Access a comprehensive set of questions on nuclear physics, reactor mechanisms, and atomic energy. Topics include nuclear fission, plasma generation, and radiation control. These physics questions form a core part of the syllabus for various engineering and civil service exams.

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Nuclear Physics and Energy Questions

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

The fission of one uranium nucleus releases energy of amount x joules. Find the number of fissions required to produced energy at the rate of v MW for t hours a nuclear power plant.

  1. $ \dfrac {yt}{x} $
  2. $ \dfrac{x}{yt} $
  3. $ 3.6 \times 10^9 \dfrac {yt}{x} $
  4. $ 3.6 \times 10^9 \dfrac {x}{yt} $
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Total energy required = Power (v MW) * time (t hours). Total energy = v * 10^6 * t * 3600 Joules. Number of fissions = Total energy / energy per fission (x). This results in the expression involving v, t, and x.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

During a nuclear fission reaction 

  1. a heavy nucleus breaks into two fragments by itself

  2. a light nucleus bombared by thermal neutrons breaks up

  3. a heavy nucleus bombared by thermal neutrons breaks up

  4. two light nuclei combine to give a heavier nucleus and possibly other products
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
In nuclear physics and nuclear chemistry, nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts, and reaction is triggered by neutron bombardment.
Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

The fissionable material used in a breeder reactor is ________

  1. $ _{92}\textrm{U}^{235}$
  2. $ _{94}\textrm{Pu}^{239}$
  3. $ _{90}\textrm{Th}^{234}$
  4. $ _{c}\textrm{C}^{12}$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Non-fissionable uranium-238 is 140 times more abundant than the fissionable U-235 and can be efficiently converted into Pu-239 by the neutrons from a fission chain reaction.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

The critical mass of $U^{235}$ can be reduced by 

  1. putting a neutron reflector around it

  2. heating it

  3. mixing impurity in it

  4. putting neutron absorber around it
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
Surrounding a spherical critical mass with a neutron reflector further reduces the mass needed for criticality. A common material for a neutron reflector is beryllium metal. This reduces the number of neutrons which escape the fissile material, resulting in increased reactivity.
Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

The most suitable material for moderator in a nuclear reactor is 

  1. $D _{2}$
  2. $Cd$
  3. $B$
  4. $ _{92}\textrm{U}^{235}$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
In nuclear reactor, a neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction.
Commonly used moderators include regular (light) water (roughly 75% of the world's reactors), solid graphite (20% of reactors) and heavy water.
Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

The fission of $U^{238}$ is possible by 

  1. only fast neutrons

  2. only slow neutrons

  3. fast as well as slow neutrons

  4. fast protons
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Uranium-23, do not usually undergo fission when struck by slow neutrons, but do split when struck with neutrons of high enough energy. The fast neutrons produced in a hydrogen bomb by fusion of deuterium and tritium have even higher energy than the fast neutrons produced in a nuclear reactor. This makes it possible to increase the yield of any given fusion weapon by the simple expedient of adding layers of cheap natural (or even depleted) uranium. Fast fission of uranium-238 provides a large part of the explosive yield, and fallout, in many designs of hydrogen bomb.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

State two safety measures to be taken while establishing a nuclear power plant.

  1. Use uranium rod and inside environment is not shielded

  2. Use uranium rod and inside environment should be shielded

  3. Use copper rod and inside environment is not shielded

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
$\rightarrow$ The nuclear energy can turn into the strong blast due to exponential growth in its reaction process. We use Uranium rods to control the reaction.
$\rightarrow$ The inside environment must be shielded from outside because its reaction with water & air causes potential health hazard.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Fast neutrons can easily be slowed down by

  1. the use of lead shielding

  2. passing them through water

  3. elastic collision with heavy nuclei

  4. applying a strong electric field
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
A neutron moderator is a medium that reduces the speed of fast neutrons, thereby turning them into thermal neutrons capable of sustaining a nuclear chain reaction.
Commonly used moderators include regular (light) water (roughly $75$% of the world's reactors), solid graphite ($20$% of reactors) and heavy water.
Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

What is the purpose of Boron rods in a nuclear reactor ?

  1. Absorb excess neutrons

  2. Absorb alpha particles

  3. Slow down the speed of neutrons

  4. Speed up the reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Boron rods are used as control rods in nuclear reactors to control the fission rate of uranium and plutonium. These are capable of absorbing many neutrons without fissioning themselves. Composition of control rods is designed for the neutron spectrum of the reactor.

Multiple choice chemistry nuclear physics nuclear reactor the nuclear power station isotopes and nuclear chemistry

Control rods in a nuclear power plant is to

  1. Slow the neutrons thereby controlling the fission reaction.

  2. Shut down the reactor.
  3. Both $(1)$ and $(2)$

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Slow the neutrons thereby controlling the fission reaction.


Control rods are used in nuclear reaction to control the fission rate of uranium and plertorium. They are composed of chemical elements such as boron, silver, indium and cadmium that are capable of absorbing many neutrons without themselves fissioning.