Explain the term stopping potential and threshold frequency.

At the stopping potential

(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.

Define threshold frequency

When a certain photosensistive surface is illuminated with monochromatic light of frequency v, the stopping potential for the photo current is -V_(0)//2 . When the surface is illuminated by monochromatic light of frequency v//2 , the stopping potential is -V_(0) . The threshold frequency gor photoelectric emission is :

Draw a graph between stopping potential and the frequency of two metals A and B having threshold frequencies v_0 and 2v_0 .

Find the frequency of light incident on a metal surface if the photocurrent is brought to zero by a stopping potential of 2.6V . The threshold frequency for the metal surface is 5xx10^(14)//s .