2 ) implies
that photoelectric emission is possible only if
h n > f0
or n > n0 , where
n0 = 
h0
φ
(11 3)
Equation (11 3) shows that the greater the work
function f0, the higher the minimum or threshold
frequency n0 needed to emit photoelectrons Thus,
there exists a threshold frequency n0 (= f0/h) for the
metal surface, below which no photoelectric  emission
is possible, no matter how intense the incident
radiation may be or how long it falls on the surface