Physics-
General
Easy
Question
Two radioactive materials 
and 
have decay constants 
and 
respectively. If initially they have the same number of nuclei, then the ratio of the number of nuclei of to that of will be 1/e after a time
The correct answer is:
and 
.
Related Questions to study
Physics-
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
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
Physics-General
Physics-
The half life of radioactive Radon is 3.8 days. The time at the end of which 
of the Radon sample will remain undecayed is (Given
)
The half life of radioactive Radon is 3.8 days. The time at the end of which of the Radon sample will remain undecayed is (Given)
Physics-General
Physics-
The electric potential between a proton and an electron is given by 
where 
is a constant. Assuming Bohr’s model to be applicable, write variation of 
with n, n being the principal quantum number
The electric potential between a proton and an electron is given by where is a constant. Assuming Bohr’s model to be applicable, write variation of with n, n being the principal quantum number
Physics-General
Physics-
A neutron with velocity V strikes a stationary deuterium atom, its kinetic energy changes by a factor of
A neutron with velocity V strikes a stationary deuterium atom, its kinetic energy changes by a factor of
Physics-General
Physics-
In a hypothetical Bohr hydrogen, the mass of the electron is doubled. The energy 
and the radius of the first orbit will be (
is the Bohr radius)
In a hypothetical Bohr hydrogen, the mass of the electron is doubled. The energy and the radius of the first orbit will be (is the Bohr radius)
Physics-General
Physics-
An energy of 24.6 eV is required to remove one of the electrons from a neutral helium atom. The energy (in eV) required to remove both the electrons from a neutral helium atom is
An energy of 24.6 eV is required to remove one of the electrons from a neutral helium atom. The energy (in eV) required to remove both the electrons from a neutral helium atom is
Physics-General
Physics-
An a-particle of 5 MeV energy strikes with a nucleus of uranium at stationary at an scattering angle of 180o. The nearest distance upto which a-particle reaches the nucleus will be of the order of
An a-particle of 5 MeV energy strikes with a nucleus of uranium at stationary at an scattering angle of 180o. The nearest distance upto which a-particle reaches the nucleus will be of the order of
Physics-General
Physics-
Mass number of Nucleus Binding energy per nucleon Vs 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
Mass number of Nucleus Binding energy per nucleon Vs 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
Physics-General
Physics-
The probability of survival of a radioactive nucleus for one mean life is
The probability of survival of a radioactive nucleus for one mean life is
Physics-General
Physics-
The collector plate in an experiment on photoelectric effect is kept vertically above the emitter plate. Light source is put on and a saturation photo current is recorded. An electric field is switched on which has a vertically downward direction
The kinetics energy of the electron will increase
The collector plate in an experiment on photoelectric effect is kept vertically above the emitter plate. Light source is put on and a saturation photo current is recorded. An electric field is switched on which has a vertically downward direction
Physics-General
The kinetics energy of the electron will increase
Physics-
If the potential difference between the anode and cathode of the X-ray tube is increases
If the potential difference between the anode and cathode of the X-ray tube is increases
Physics-General
Physics-
The maximum velocity of electrons emitted from a metal surface is V. When frequency of light falling on it is f. The maximum velocity when frequency becomes 4f is
The maximum velocity of electrons emitted from a metal surface is V. When frequency of light falling on it is f. The maximum velocity when frequency becomes 4f is
Physics-General
Physics-
Two large parallel plates are connected with the terminal of 100 V power supply. These plates have a fine hole at the centre. An electron having energy 200 eV is so directed that it passes through the holes. When it comes out it's de-Broglie wavelength is
Two large parallel plates are connected with the terminal of 100 V power supply. These plates have a fine hole at the centre. An electron having energy 200 eV is so directed that it passes through the holes. When it comes out it's de-Broglie wavelength is
Physics-General
Physics-
If light of wavelength 
is allowed to fall on a metal, then kinetic energy of photoelectrons emitted is 
. If wavelength of light changes to 
then kinetic energy of electrons changes to 
. Then work function of the metal is
If light of wavelength is allowed to fall on a metal, then kinetic energy of photoelectrons emitted is . If wavelength of light changes to then kinetic energy of electrons changes to . Then work function of the metal is
Physics-General
Physics-
Light of wavelength 2475 Å is incident on barium. Photoelectrons emitted describe a circle of radius 100 cm by a magnetic field of flux density 
Tesla. Work function of the barium is (Given 
Light of wavelength 2475 Å is incident on barium. Photoelectrons emitted describe a circle of radius 100 cm by a magnetic field of flux density Tesla. Work function of the barium is (Given
Physics-General
