When a photon is emitted by a hydrogen atom, the photon carries a momentum with it.

(a) Calculate the momentum carried by the photon when a hydrogen atom emits light of wavelength 656.3 nm

(b) With what speed does the atom recoil during this transition? Take the mass of the hydrogen atom = 1.67 × 10^–27 kg.

(c) Find the kinetic energy of recoil of the atom.

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.

A neutron moving with a speed v strikes a hydrogen atom in ground state moving towards it with the same speed. Find the minimum speed to the neutron for which inelastic (completely or partially) collision may take place. The mass of neutron = mass of hydrogen = 1.67 × 10^–27 kg.

When a photon is emitted from an atom, the atom recoils. The kinetic energy of recoil and the energy of the photon come from the difference in energies between the states involved in the transition. Suppose, a hydrogen atom changes its state from n = 3 to n = 2. Calculate the fractional change in the wavelength of light emitted, due to the recoil.

The light emitted in the transition n = 3 to n = 2 in hydrogen is called H_α light. Find the maximum work function a metal can have so that H_α light can emit photoelectrons from it.