question_answer

According to Einstein's photoelectric equation, the graph between the kinetic energy of photo- electrons ejected and the frequency of incident radiation is

A)  

B)

C)

D)

Correct Answer: D

Solution :

 According to Einstein's photoelectric equation \[hv=h{{v}_{0}}+{{K}_{\max }}\Rightarrow {{K}_{\max }}=hv-h{{v}_{0}}\] \[K{{E}_{\max }}=hv-\phi \]                                          ?(i) where \[\phi =\]work function of metal Comparing above Eq. (i) with equation of a straight line\[~y=mx+c\] we get \[m=h,\,c=-\phi \] Therefore, if we draw a graph between kinetic energy and frequency, then a straight line cutting the frequency axis at vq and giving an intercept of \[(-\phi )\] on the kinetic energy axis is obtained.