Threshold frequency for a metal is 1015 Hz. If the light of wavelength 4000 A falls on its surface, then which of the following statement is correct?
(a) Photoelectrons come out with a velocity of 100 m/sec
(b) No photoelectric emission takes place
(c) Photoelectrons come out with a velocity of 124 m/sec
(d) Photoelectrons come out with a velocity of 9.8 m/sec
