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 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

A neutron with velocity V strikes a stationary deuterium atom, its kinetic energy changes by a factor of

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)

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 a-particle of 5 MeV energy strikes with a nucleus of uranium at stationary at an scattering angle of 180^o. The nearest distance upto which a-particle reaches the nucleus will be of the order of

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

The probability of survival of a radioactive nucleus for one mean life is

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

If the potential difference between the anode and cathode of the X-ray tube is increases

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

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

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

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

The figure shows different graphs between stopping potential and frequency (n) for photosensitive surface of cesium, potassium, sodium and lithium. The plots are parallel. Correct ranking of the targets according to their work function greatest first will be

 

An electron is moving through a field. It is moving (i) opposite an electric field (ii) perpendicular to a magnetic field as shown. For each situation the de-Broglie wave length of electron