The momentum of a photon of energy 1 MeV in kg m/s will be

In a discharge tube ionization of enclosed gas is produced due to collisions between

The work functions for metals A, B and C are respectively 1.92 eV, 2.0 eV and 5 eV. According to Einstein's equation the metals which will emit photoelectrons for a radiation of wavelength 4100 $$\mathop A\limits^ \circ $$ is/are

A photosensitive metallic surface has work function, h$$\upsilon $$₀. If photons of energy $$2h{\upsilon _0}$$ fall on this surface, the electrons come out with a maximum velocity of 4 $$ \times $$ 10⁶ m/s. When the photon energy is increased to 5 h$$\upsilon $$₀, then maximum velocity of photoelectrons will be