In a photoelectric cell, wavelength of the incident light is changed from 4000A⁰ to 3600A⁰. Change in stopping potential will be nearly

At least how many thermal neutrons should be available to start a fission reaction

₇N¹⁴+₂He⁴→X+₁H¹ then ‘X’ is

In a full wave rectifier output is taken across a load resistor of 800ohm.If the resistance of diode in forward biased condition is 200 ohm,the efficiency of reflection of rectification of ac power into dc power is

The energy released by fission from 2g of ²³⁵₉₂U in KWH is.(The energy released per fission is 200MeV).

In Millikans oil drop experiment, an oil drop of radius r charge q falls under the gravity with a terminal velocity V_g and moves up with a terminal velocity V_e in the uniform vertical electric field of intensity E. If η is coefficient of viscosity of air, the charge of oil drop is

An explosion of atomic bomb releases an energy of 7.6x10¹³J.If 200 MeV energy is released on fission of one ²³⁵U atom the number of uranium atoms undergoing fission,and the mass of uranium used in the bomb is

A photo-cathode is irradiated in turn by light of wavelengths 4000 A⁰ and 6200 A⁰ respectively. The ratio of the stopping potentials in the two cases is found to be 2:1. The work function of the photo-cathode is nearly

An electron beam moving with a speed of 2x10⁷ms^-1 enters a magnetic field of induction 3x10^-3T, directed perpendicular to its direction of motion. The intensity of electric field applied so that the electron beam is undeflected due to the magnetic field is

An intrinsic semi conductor has 10¹⁸/m³ free electron and is doped with pentavalent impurity of 10²⁴/m³.Then the free electrons density order increases by