question_answer

Green light ejects photoelectrons from a given photosensitive surface whereas yellow light does not. What will happen in case of

(i) violet, and

(ii) red light?

Give reason for your answer.

Answer:

As photoelectric emission takes place for green light but does not take place for yellow light. Hence, threshold wavelength \[{{\lambda }_{0}}\] lies somewhere between them.

(i) When incident light is of violet colour, its wavelength is even less than that of green light, i.e. \[\lambda <{{\lambda }_{0}},\] as a result, photoelectric emission will definetly take place.

(ii) When incident light is of red colour, its wavelength is even greater than that of yellow light, i.e. \[\lambda >{{\lambda }_{0}},\] consequently, no photoelectric emission will take Place.