(a) State three important properties of photons which describe the particle picture of electromagnetic radiation.
(b) Use Einstein's photoelectric equation to define the terms (i) stopping potential and (ii) threshold frequency.

Write the basic features of photon pictures of electromagnetic radiation on which Einstien's photoelectric equation is based.

(a) Why photoelectric effect cannot be explained on the basis of wave nature of light? (b) Write the basic features of photon picture of electromagnetic radiation on which Einstein's photoelectric equation is based.

Derive de Broglie wave equation for material particles. (b) Why does photoelectric emission not take place if the frequency of incident radiation is less than threshold frequency ?

State how in a photo-cell, the work function of the metal influence the kinetic energy of the emitted electrons. (a) If the intensity of the incident radiation is doubled, what change occur in (i) the stopping potential and (ii) in photoelectric current? (b) If the frequency of the incident radiation is doubled, what changes occur in the (i) stopping potential and (ii) photoelectric current.