Electrons are emitted from an electron gun at almost zero velocity and are accelerated by an electric filed E through a distance of 1.0 m. The electrons are now scattered by an atomic hydrogen sample in ground state. What should be the minimum value of E so that red light of wavelength 656.3 nm may be emitted by the hydrogen?

A parallel beam of light of wavelength 100 nm passes through a sample of atomic hydrogen gas in ground state.

(a) Assume that when a photon supplies some of its energy to a hydrogen atom, the rest of the energy appears as another photon moving in the same direction as the incident photon. Neglecting the light emitted by the excited hydrogen atoms in the directions of the incident beam. What wavelengths may be observed in the transmitted beam?

(b) A radiation detector is placed near the gas to detect radiation coming perpendicular to the incident beam. Find the wavelengths of radiation that may be detected by the detector.

A beam of monochromatic light of wavelength λ ejects photoelectrons from a cesium surface (ϕ = 1.9 eV). These photoelectrons are made to collide with hydrogen atoms is ground state. Find the maximum value of λ for which

(a) hydrogen atoms may be ionized,

(b) hydrogen atoms may get excited from the ground state to the first excited state and

(c) the excited hydrogen atoms may emit visible light.

A neutron having kinetic energy 12.5 eV collides with a hydrogen atom at rest. Neglect the difference in mass between the neutron and the hydrogen atom and assume that the neutron does not leave its line of motion. Find the possible kinetic energies of the neutron after the even.

A hydrogen atom moving at speed v collides with another hydrogen atom kept at rest. Find the minimum value of v for which one of the atoms may get ionized. The mass of a hydrogen atom = 1.67 × 10^–27 kg.