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An important facility for 12th class students preparing for short questions physics 12th class chapter 10 of BISE. Get hundreds of questions to prepare and get better marks in 12th physics
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Question: 1
How energy released when 1 amu converted into energy?
Answer: 1
1-52
1 amu= 1.66 x10-27kg

the energy of 1 amu is 1 amu =1.494 x10-10J
1 amu= 931 MeV
Question: 2
If nucleus has a life of one year,does this mean that it will be completely decayed after two years?
Answer: 2
2-52
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: 3
What are the relation between decay constantλand the half-line of a radioactive element?
Answer: 3
3-52
The relation between decay constantλand the half line (T1/2) isλT1/2=0.693
Question: 4
A particle which produce more ionization ,is less penetrating.Why?
Answer: 4
4-52
A particle with great power loses large amount of energy for small distances.That is,it produces more ionization but is less penetration.
Question: 5
Why are heavy nuclei unstable?
Answer: 5
5-52
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.
Question: 6
What is half line?
Answer: 6
6-52
The half line T1/2of a radioactive elements is that period in which half of the atoms decay.
Question: 7
What are isotopes?What do they have common and what are their difference.
Answer: 7
7-52
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: 8
Define decay constant.
Answer: 8
8-52
Decay constant of any element is to the fraction of the decaying atoms per unit time.
Question: 9
Differentiate between parent and daughter element.
Answer: 9
9-52
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: 10
What do you mean by critical mass and critical volume?
Answer: 10
10-52
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: 11
Define mass defect and binding energy.
Answer: 11
11-52
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: 12
What are isotopes?What do you have in common?
Answer: 12
12-52
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: 13
What do you understand by "background radiation "?State two source of this radiation?
Answer: 13
13-52
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: 14
Describe the principle of operation of solid state detector.
Answer: 14
14-52
The principle of operation of solid state detector is based upon the production of electron-hole pair to cause a pulse of current.
Question: 15
Write down two advantages of solid state detector over geiger muller counter.
Answer: 15
15-52
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: 16
What information if revealed by the length and shape of track of an incident particle in Wilson Cloud Chamber?
Answer: 16
16-52
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: 17
What is self-quenching in Geiger Muller Counter?
Answer: 17
17-52
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: 18
How alpha and beta may ionize an atom without directly hitting the electrons?
Answer: 18
18-52
As alpha and beta are electrically charged particle,so they can cause ionization without hitting an atom either by,repellings the electron of target particle.
Question: 19
Describe a brief account of interaction of various types of radiations with matter.
Answer: 19
19-52
  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: 20
What are thermal reactors?
Answer: 20
20-52
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: 21
What do you know about Radioactivity?
Answer: 21
21-52
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: 22
Briefly give the use of (a)Wilson cloud chamber (b)G.M counter.
Answer: 22
22-52
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: 23
Describe the principle of operation of solid state detector?
Answer: 23
23-52
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: 24
Why moderators are used in the core of nuclear reactor?
Answer: 24
24-52
The moderator ae used in the core to slow the neutrons down so that they can be captured and keep the chain reaction going.
Question: 25
Define fission and fusion reaction.
Answer: 25
25-52
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: 26
Define nuclear fission.
Answer: 26
26-52
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: 27
Differentiate between controlled and uncontrolled reaction.
Answer: 27
27-52
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: 28
If you swallowed a alpha source and beta source ,which would be more dangerous to you ?Explain
Answer: 28
28-52
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: 29
What factor make a Fusion reaction difficult to achieve?
Answer: 29
29-52
A fusion reaction requires large energy and temperature ,up to million degrees centigrades,So a fusion reaction is difficult to achieve.
Question: 30
Define background radiations.What are their sources?
Answer: 30
30-52
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 Earth's crest.
  3. Radioactive potassium and carbon in the body.
Question: 31
Discuss the advantage and disadvantage of nuclear power compare to the use of fossil fuel generated power.
Answer: 31
31-52
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 injurous and harmful to living things.
  3. Nuclear waste can not be transported through area of population whereas fossil fuel can be.
Question: 32
Wh Geiger counter is not suitable for fast counting?
Answer: 32
32-52
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: 33
What is radioactive tracer?Give its one application each in industry and medicine.
Answer: 33
33-52
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: 34
Distinguished between nuclear fission and nuclear fusion.
Answer: 34
34-52
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: 35
How can radioactivity help in the treatment of cancer?
Answer: 35
35-52
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: 36
Discuss the advantages of fission power from point of view of safety,pollution and resources.
Answer: 36
36-52
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: 37
Name the basic forces of nature.
Answer: 37
37-52
The basic forces of nature are
  1. Gravitational force
  2. Electromagnetic force
  3. Weak nuclear force
  4. Strong nuclear force
Question: 38
Differentiate between Baryons and Mesons.
Answer: 38
38-52
Baryons:The particle equal in mass greater than protons are called baryons.It is made by 3 quarks.

Question: 39
Protons and neutron are formed by what types of quarks?
Answer: 39
39-52
Protons is formed by two up and one down quarks.Neutron is formed by two down and one up quarks.
Question: 40
What is meant by dose of radiation?What is its SI units?
Answer: 40
40-52
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: 41
Define absorbed dose and Gray.
Answer: 41
41-52
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: 42
State two characteristics of beta particle.
Answer: 42
42-52
They are negatively charged particle.
Their penetration power is high.
Question: 43
Which radiation does would deposit more energy to the body(a)10 m Gy to the hand (b)1m Gy dose to entire body.
Answer: 43
43-52
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: 44
Briefly describe the term radiography.
Answer: 44
44-52
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: 45
Define Half line and discuss its dependence.
Answer: 45
45-52
The half line T1/2of 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: 46
Write name of different quarks.
Answer: 46
46-52
The name of different quarks are as follows
Up,Down-Strange ,Charm,Top,Bottom
Question: 47
Define Hadrons and Leptons.
Answer: 47
47-52
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 laptons are electrons .muons and neutrinos etc.
Question: 48
What do you mean by quark?
Answer: 48
48-52
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: 49
What is radioactivity decay?Give an example.
Answer: 49
49-52
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: 50
Define half-line of radioactive element.How is it related with decay constant?
Answer: 50
50-52
Half-line:T1/2is 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: 51
What is the function of control rods in nuclear reactor?
Answer: 51
51-52
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: 52
Write names of hydrogen isotopes.
Answer: 52
52-52
Three isotopes of hydrogen are:
  1. Protium
  2. Deuterium
  3. Tritium