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A monochromatic light of wavelength lambda is incident on an isolated metallic sphere of radius a. The threshold wavelength is lambda_(0) which is larger then lambda. A monochromatic light of wavelength lambda is incident on an isolated metallic sphere of radius a. The threshold wavelength is lambda_(0) which is larger then lambda. September 4, 2021 [...]

A beam of white light is incident normally on a plane surface absorbing 70% of the light and reflecting the rest. If the incident beam carries 20 W of power, find the force exerted by it on the surface. A beam of white light is incident normally on a plane surface absorbing 70% of the [...]

Ionization energy of a hydrogen-like ion A is greater than that of another hydrogen-like ion B. Let, r, u, E and L represent the radius of the orbit, speed of the electron, energy of the atom and orbital angular momentum of the electron respectively. In ground state E and L represent the radius of the [...]

Half lives of two isotopes X and Y of a material are known to be 2×10^9 years and 4×10^9 years respectively. Planet was formed with equal number of these isotopes, and currently the material has 20% of X and 80% of Y by number on the planet. The current age of the planet is and [...]

Suppose the potential energy between electron and proton at a distance r is given by U = – (ke^2/3r^3) . Assuming Bhor’s Model to be valid for this atom if the speed of electron in nth Suppose the potential energy between electron and proton at a distance r is given by U = - (ke^2/3r^3) [...]

Consider the following energies 1. The minimum energy needed to excite a hydrogen atom from its ground state -E_(1). (2) Energy needed to ionize a hydrogen atom from ground state =E_(2) Consider the following energies 1. The minimum energy needed to excite a hydrogen atom from its ground state -E_(1). (2) Energy needed to ionize [...]

The half-life of 92 238 ​U undergoing α−decay is 4.5 ×10^9 years. The activity of the 1g sample of 92 238 ​U is? The half-life of 92 238 ​U undergoing α−decay is 4.5 ×10^9 years. The activity of the 1g sample of 92 238 ​U is? September 4, 2021 Category: Arihant Physics by D.C Pandey [...]

In a Coolidge tube, the potential difference used to accelerate the electrons is increased from 12.4 kV to 24.8 kV. As a result, the difference between the wavelengths of K_(alpha)-line and minimum wavelength increases to thrice its former value. The wavelength of the K_(alpha) line is (hc)/(e)=(12.4 KVA) In a Coolidge tube the difference between [...]

Assuming that about 20 MeV of energy is released per fusion reaction, 1H^2 + 1H^3 ⟶ 2He^4 . then the mass of 1H^2 consumed per day in a fusion reactor of power 1 MW will approximately be : 1H^2 + 1H^3 ⟶ 2He^4 . then the mass of 1H^2 consumed per day in a fusion [...]

Two identical photocathodes receive light of frequencies f1 ​and f2 . If the velocities of the photoelectrons (of mass m) coming out are v1 ​ and v2 , respectively, then respectively then Two identical photocathodes receive light of frequencies f1 ​and f2 . If the velocities of the photoelectrons (of mass m) coming out are [...]