When light of sufficiently high frequency is incident on a metallic surface, electrons are emitted from the metallic surface. This phenomenon is called photoelectric emission. Kinetic energy of the emitted photoelectrons depends on the wavelength of incident light and is independent of the intensity of light. Number of emitted photoelectrons depends on intensity. `(hv-phi)` is the maximum kinetic energy of emitted photoelectron (where `phi` is the work function of metallic surface). Reverse effect of photo emission produces X-ray. X-ray is not deflected by electric and magnetic fields. Wavelength of a continuous X-ray depends on potential difference across the tuve. Wavelength of charasteristic X-ray depends on the atomic number.
Q. If frequency `(upsilongtupsilon_0)` of incident light becomes n times the initial frequency (v), then KE of the emitted photoelectrons becomes (`v_0` threshold frequency).