Physics

JAMB 1984

Which of the following statements is (are) NOT true about the emission of the photoelectrons from metallic surfaces?

i. all metallic surfaces emits the same number of photoelectrons in a given light

ii. most metallic surfaces emit the same number of photoelectrons in visible and infra-red light

iii. a metallic surface emits photoelectrons only if the frequency of the incident light is higher than its own characteristics threshold frequency