Physics-
General
Easy
Question
Cadmium rods are used in a nuclear reactor for
- Slowing down fast neutrons
- Speeding up slow neutrons
- Absorbing neutrons
- Regulating the power level of reactor.
The correct answer is: Absorbing neutrons
Cadmium rods are used in the form of control rods. In a nuclear reactor the material that can absorb the neutrons are used to control the nuclear chain reaction. Cadmium and Boron rods are used for this purpose.
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To determine the half- life of radioactive element, a student plots graph of ln
t. Here 
is the rate of radioactive decay at time t. If the number of radioactive nuclei of this element decreases by a factor of 
after 4.16 yr, the value of is
To determine the half- life of radioactive element, a student plots graph of ln t. Here is the rate of radioactive decay at time t. If the number of radioactive nuclei of this element decreases by a factor of after 4.16 yr, the value of is
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In Bohr model of hydrogen atom, the force on the electron depends on the principal quantum number as
In Bohr model of hydrogen atom, the force on the electron depends on the principal quantum number as
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Assertion : All the radioactive elements are ultimately converted in lead.
Reason : All the elements above lead are unstable.
Assertion : All the radioactive elements are ultimately converted in lead.
Reason : All the elements above lead are unstable.
Physics-General
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Assertion : Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate.
Reason : According to classical physics all moving electrons radiate.
Assertion : Bohr had to postulate that the electrons in stationary orbits around the nucleus do not radiate.
Reason : According to classical physics all moving electrons radiate.
Physics-General
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The figure shows a graph between 
and ln|n|, where 
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The graph which represents the correct variation of logarithm of activity (log A) versus time, in figure is
The graph which represents the correct variation of logarithm of activity (log A) versus time, in figure is
Physics-General
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In Fig. X represents time and Y represent activity of a radioactive sample. Then the activity of sample, varies with time according to the curve
In Fig. X represents time and Y represent activity of a radioactive sample. Then the activity of sample, varies with time according to the curve
Physics-General
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Binding energy per nucleon verses mass number curve for nuclei is shown in the figure. W, X, Y and Z are four nuclei indicated on the curve. The process that would release energy is
Binding energy per nucleon verses mass number curve for nuclei is shown in the figure. W, X, Y and Z are four nuclei indicated on the curve. The process that would release energy is
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The fraction f of radioactive material that has decayed in time t, varies with time t. The correct variation is given by the curve
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The count rate of 10g of radioactive material was measured at different times and this has been shown in the figure. The half life of material and the total counts (approximately) in the first half life period, respectively are
The count rate of 10g of radioactive material was measured at different times and this has been shown in the figure. The half life of material and the total counts (approximately) in the first half life period, respectively are
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Binding energy per nucleon plot against the mass number for stable nuclei is shown in the figure. Which curve is correct
Binding energy per nucleon plot against the mass number for stable nuclei is shown in the figure. Which curve is correct
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The graph between wave number 
and angular frequency (w) is
The graph between wave number and angular frequency (w) is
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An atomic power nuclear reactor can deliver 300 MW. The energy released due to fission of each nucleus of uranium atom 
is 170 MeV. The number of uranium atoms fissioned per hour will be
An atomic power nuclear reactor can deliver 300 MW. The energy released due to fission of each nucleus of uranium atom is 170 MeV. The number of uranium atoms fissioned per hour will be
Physics-General
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The half life of radium is 1620 years and its atomic weight is 226 kgm per kilomol. The number of atoms that will decay from its 1 gm sample per second will be (Avogadro's number 
atom/kilomol)
The half life of radium is 1620 years and its atomic weight is 226 kgm per kilomol. The number of atoms that will decay from its 1 gm sample per second will be (Avogadro's number atom/kilomol)
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In the Bohr model of the hydrogen atom, let R, v and E represent the radius of the orbit, the speed of electron and the total energy of the electron respectively. Which of the following quantity is proportional to the quantum number n
In the Bohr model of the hydrogen atom, let R, v and E represent the radius of the orbit, the speed of electron and the total energy of the electron respectively. Which of the following quantity is proportional to the quantum number n
Physics-General
