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Chapter 21 Nuclear Physics Physics 12th Class Punjab Short Questions

Question No. 1 - Differentiate between parent and daughter element.

Answer No. 1 - The change of an element into a new element due to emission of radiation is called radioactive decay. The original atom is called parent element and the element formed due to this decay is called daughter element.

Question No. 2 - A particle which produce more ionization is less penetrating. Why?

Answer No. 2 - A particle with great power loses large amount of energy for small distances. That is it produces more ionization but is less penetration.

Question No. 3 - What information if revealed by the length and shape of track of an incident particle in Wilson Cloud Chamber?

Answer No. 3 - In a Wilson Cloud Chamber:
1. Alpha particle have larger mass and greater ionizing
power so its path is straight.
2. Beta particle have less mass and less ionizing power, so
its path is thinner shorter and discontinuous.
3. Gamma particle have no mass and high penetrating
power, so its leaves no definite track along its path.

Question No. 4 - What is radioactive tracer? Give its one application each in industry and medicine.

Answer No. 4 - Radioactive tracer is a radioactive isotope which acts as an indicator or tracer that makes it possible to follow the course of a chemical or biological process. They are used in:
1. Medicine to detect malignant tumors.
2. Agriculture to study the uptake of a fertilizer by a
plant.

Question No. 5 - Describe the principle of operation of solid state detector.

Answer No. 5 - The principle of operation of solid state detector is based upon the production of electron-hole pair to cause a pulse of current.

Question No. 6 - Protons and neutron are formed by what types of quarks?

Answer No. 6 - Protons is formed by two up and one down quarks. Neutron is formed by two down and one up quarks.

Question No. 7 - Describe the principle of operation of solid state detector?

Answer No. 7 - A solid state detector is a specially designed p-n junction operating under a reversed bias in which electron-hole pairs are produced by the incident radiation to cause a current pulse to flow through the external circuit.

Question No. 8 - Briefly give the use of a Wilson Cloud Chamber b G.M counter.

Answer No. 8 - Wilson Cloud Chamber: It provides information about the change in mass and energy of radiating particles.
G.M Counter: It is used to determine the range and penetrating power of ionizing particles.

Question No. 9 - Discuss the advantage and disadvantage of nuclear power compare to the use of fossil fuel generated power.

Answer No. 9 - Advantage and disadvantage of nuclear power are given below compared to the use of fossil generated power.
Advantage:
1. Much more energy is produced.
2. Produces no environmental pollution.
3. Electricity produced in this way is far cheaper than
fossil fuel generated power.
Disadvantage :
1. Uranium mining is more dangerous than coal mining.
2. Nuclear waster is very injurious and harmful to living
things.
3. Nuclear waste can not be transported through area of
population whereas fossil fuel can be.

Question No. 10 - If nucleus has a life of one year, does this mean that it will be completely decayed after two years?

Answer No. 10 - No it will not decay completely after two years.
Numbers of atom at initial stage = No
number of atoms decayed after first year =1/2No

Question No. 11 - What are thermal reactors?

Answer No. 11 - The thermal reactors are called thermal reactors because the neutrons must be slowed down to thermal energies to produce further fission. They use natural uranium or slightly enriched uranium as fuel.

Question No. 12 - Name the basic forces of nature.

Answer No. 12 - The basic forces of nature are:
1. Gravitational force
2. Electromagnetic force
3. Weak nuclear force
4. Strong nuclear force

Question No. 13 - Why moderators are used in the core of nuclear reactor?

Answer No. 13 - The moderator are used in the core to slow the neutrons down so that they can be captured and keep the chain reaction going.

Question No. 14 - What factor make a Fusion reaction difficult to achieve?

Answer No. 14 - A fusion reaction requires large energy and temperature, up to million degrees centigrade, So a fusion reaction is difficult to achieve.

Question No. 15 - Discuss the advantages of fission power from point of view of safety, pollution and resources.

Answer No. 15 - Advantage of nuclear power are given below:
1. Nuclear fission energy, release a highly reduced amount
of the gases into the air, resulting in a slower rate of
global warming and pollution.
2. The energy is quick to create; meaning that they are
able to make a large amount of some form of emergency
required it.
3. Much more energy is produced.

Question No. 16 - Write down two advantages of solid state detector over Geiger Muller counter.

Answer No. 16 - Solid state detector can count very fast than gas filled detector.
Solid state detector is much smaller in size.
It operates at low voltage.

Question No. 17 - State two characteristics of beta particle.

Answer No. 17 - They are negatively charged particle.
Their penetration power is high.

Question No. 18 - Differentiate between Baryons and Mesons.

Answer No. 18 - Baryons: The particle equal in mass greater than protons are called baryons. It is made by 3 quarks.

Question No. 19 - How alpha and beta may ionize an atom without directly hitting the electrons?

Answer No. 19 - As alpha and beta are electrically charged particle, so they can cause ionization without hitting an atom either by, repelling the electron of target particle.

Question No. 20 - What do you understand by "Background Radiation "? State two source of this radiation?

Answer No. 20 - When no radioactive source is placed near the radiation detector, it records radiation. These radiations are called background radiations.
Its source are:
1. Cosmic rays
2. Presence of radioactive substance Earth crust and
atmosphere.

Question No. 21 - What are isotopes? What do they have common and what are their difference.

Answer No. 21 - Isotopes are such nuclei of an element that have the same charge number Z but have different mass number A. It means in the nucleus the number of protons is the same but the number of neutrons is different.

Question No. 22 - What are isotopes? What do you have in common?

Answer No. 22 - Isotopes are such nuclei of an element that have the same charge number Z but have different mass number A.
It means, in the nucleus the number of protons is the same but the number of neutrons is different.

Question No. 23 - What is the function of control rods in nuclear reactor?

Answer No. 23 - Controls rods made of Cadmium or Boron are used for the control of number of neutrons, so that of all the neutrons produced in fission, only one neutrons produces further fission reaction.
In case of emergency or for repair purpose control rods are used to stop the chain reaction and shut down the reactor.

Question No. 24 - Why Geiger Counter is not suitable for fast counting?

Answer No. 24 - Geiger counter is not suitable for fast counting because of its longer dead time. The positive ions take several time as long to reach the outer cathode, because positive ions are very massive than the electrons. During this time further incoming particle can not be counted. This time is called as the dead time of counter which delays fast counting system.

Question No. 25 - Distinguished between nuclear fission and nuclear fusion.

Answer No. 25 - Nuclear Fission: Such a reaction in which a heavy nuclei like that of uranium splits up into two of roughly equal size along with the emission of energy is called fission reaction.

Question No. 26 - Define nuclear fission.

Answer No. 26 - Such a reaction in which a heavy nucleus like that of uranium splits up into two nuclei of roughly equal size along with the emission of energy is called fission reaction.

Question No. 27 - Define decay constant.

Answer No. 27 - Decay constant of any element is to the fraction of the decaying atoms per unit time.

Question No. 28 - Define absorbed dose and Gray.

Answer No. 28 - Absorbed dose: It is defined as the amount of energy absorbed from an ionizing radiation per unit mass of the absorbing body i.e.
Absorbed dose=energy/mass
Gray: it is defined as the amount of energy equal to one joule absorbed by a body of mass 1kg i.e.
gray=1 joule/1 kg

Question No. 29 - Define fission and fusion reaction.

Answer No. 29 - Fission: Such a reaction in which a heavy nucleus like that of uranium splits up into two nuclei of roughly equal size along with the emission of energy is called fission reaction.

Question No. 30 - What do you mean by quark?

Answer No. 30 - Quark is the basic building block of mesons and baryons. In actual it is the basic building block matter. It is proposed by Murray Gell-Mann and G.Zweig. It is of six types: Up, Down-Strange, Charm, Bottom and Top.

Question No. 31 - What is radioactivity decay? Give an example.

Answer No. 31 - The emission of radiations from elements having charge number Z greater than 82 is called radioactivity or radioactive decay.
The emission of an a-particle from radium-226, result in the formation of radon gas.

Question No. 32 - Write names of hydrogen isotopes.

Answer No. 32 - Three isotopes of hydrogen are:
1. Protium
2. Deuterium
3. Tritium

Question No. 33 - Differentiate between controlled and uncontrolled reaction.

Answer No. 33 - To maintain a sustained controlled nuclear reaction for every 2 or 3 neutrons released, only one must be allowed to strike another uranium nucleus. It is called controlled chain reaction.

Question No. 34 - How energy released when 1 AMU converted into energy?

Answer No. 34 - 1 amu = 1.66 x10^-27kg

The energy of 1 amu is 1 amu =1.494 x10^-10J
1 amu = 931 MeV

Question No. 35 - Describe a brief account of interaction of various types of radiations with matter.

Answer No. 35 - 1. An a particle has well defined range in a medium, before
coming to rest which is called range if a-particle.
2. It lose its energy due to excitation and ionization of
atoms and molecules in matter.

Question No. 36 - What is half line?

Answer No. 36 - The half line T1/2 of a radioactive elements is that period in which half of the atoms decay.

Question No. 37 - Briefly describe the term radiography.

Answer No. 37 - The radiography is a technique used in medicine such as internal imaging of the brain to determine the size and location of the tumor precisely.

Question No. 38 - If you swallowed a alpha source and beta source, which would be more dangerous to you? Explain.

Answer No. 38 - As alpha particle have greater energy and ionizing power than beta particle, so alpha particle are more dangerous than beta particle.
Critical volume: The volume of critical mass is called critical volume.

Question No. 39 - Which radiation does would deposit more energy to the bodya 10 m Gy to the hand b 1m Gy dose to entire body.

Answer No. 39 - Since
absorbed dose=D=energy/mass
energy=D * Mass
since the mass of whole body is much greater than mass of the hand, therefore 1 Gy dose given to the entire body deposit more energy.

Question No. 40 - How can radioactivity help in the treatment of cancer?

Answer No. 40 - It helps in treatment of cancer:
1. Cobalt-60 is used in radiotherapy.
2. For skin cancer, phosphorus -32 or strontium-9 is used.
3. Radioactive iodine-131 is used to cure cancer of thyroid
gland.

Question No. 41 - What is meant by dose of radiation? What is its SI units?

Answer No. 41 - Radiation dose is a measure of the amount of exposure to radiation. There are three kinds of dose:
1. Absorbed dose: It is the amount of energy deposited by
radiation in a mass.
D=E/m its SI unit is Gy.
2. Equivalent dose: It is calculated for individual organ
De=D*RBE
3. Effective dose: It is calculated for the whole body, It
is also measured ni Sv.

Question No. 42 - Define background radiations. What are their sources?

Answer No. 42 - When no radioactive source is placed near the radiations detector, it records radiations. These radiations are called background radiations.
Its source are:
1. The cosmic rays which come to us from outer space.
2. Radioactive substance present is the Earths crest.
3. Radioactive potassium and carbon in the body.

Question No. 43 - What do you mean by critical mass and critical volume?

Answer No. 43 - The mass of uranium in which one neutron out of all neutron out of all neutron produced in one fission reaction produces further fission reaction is called critical mass.

Question No. 44 - Define half-line of radioactive element. How is it related with decay constant?

Answer No. 44 - Half-line: T1/2 is the period in which half of the atom of a radioactive element decay.
It is related with a decay constant by formula.
T1/2= 0.693/Λ

Question No. 45 - What do you know about Radioactivity?

Answer No. 45 - The elements having charge number Z>82 are unstable and they emit invisible radiations which affect the photographic plate. Such element are called radioactive elements and this process is called radioactivity.

Question No. 46 - Define Hadrons and Leptons.

Answer No. 46 - Hadrons: These are not elementary particle. They are composed of other elementary particle called quarks. The example of hadrons are protons, neutrons, mesons etc. They experience strong nuclear force.
Laptons: The are elementary particles. They do not experience strong nuclear force. The example of leptons are electrons. Muons and neutrinos etc.

Question No. 47 - What is self-quenching in Geiger Muller Counter?

Answer No. 47 - A small amount of gas is added into the GM counter is called self quenching or internal quenching. In GM counter the phenomena of quenching is to save the counter from spurious or false counts.

Question No. 48 - Define Half line and discuss its dependence.

Answer No. 48 - The half line T1/2 of a radioactive elements is that period in which half of the atom decay.
Dependence: The number of decaying atoms is proportional to the number of atoms present in the beginning of the period and is proportional to time interval.

Question No. 49 - Define mass defect and binding energy.

Answer No. 49 - Mass Defect: The mass of the nucleus is always less than the total mass of the protons and neutrons that make up the nucleus. The difference of the two masses is called mass defect.
Binding Energy: The missing mass is converted into energy at the formation of the nucleus and is called binding energy.

Question No. 50 - Write name of different quarks.

Answer No. 50 - The name of different quarks are as follows:
Up, Down-Strange, Charm, Top, Bottom

Question No. 51 - Why are heavy nuclei unstable?

Answer No. 51 - Heavy nuclei are unstable because their binding energy per nucleon is less than lighter nuclei. So less energy is required to break heavy nuclei and they become unstable.

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