A photon, an electron and a uranium nucleus all have the same wavelength. The one with the most energy

Two streams of photons, possessing energies to five and ten times the work function of metal are incident on the metal surface successively. The ratio of the maximum velocities of the photoelectron emitted, in the two cases respectively, will be.

An electron and proton are separated by a large distance. The electron starts approaching the proton with energy $3\, {eV}$. The proton captures the electrons and forms a hydrogen atom in second excited state. The resulting photon is incident on a photosensitive metal of threshold wavelength $4000\, \mathring {{A}}$. What is the maximum kinetic energy of the emitted photoelectron ? (In ${eV}$)

The number of photons emitted by a $10\,watt$ bulb in $10\,second,$ if wavelength of light is $1000\,\,\mathop A\limits^o ,$ is

The energy equivalent to $1\,mg$ of matter in $MeV$ is

The mass of a photo electron is