[figure] Which of the following statements are correct, if the threshold frequency of caesium is 5.16 1014 Hz? Choose the correct answer from the options given below:
- B, C and D Only
- A, C, D and E Only
- A, B, D and E Only
- A, D and E Only
Answer
(3) A, B, D and E Only
Solution
Threshold wavelength:
0 = c 0 = 3.0 1085.16 1014
= 5.81 10-7 m = 581 nm
Only light with < 581 nm ( > 0) ejects photoelectrons.
A: Yellow light in the given spectrum lies below 581 nm > 0 current flows. True
B: Dimming lowers the intensity fewer photons fewer photoelectrons smaller current. True
C: Red light ( 620–750 nm) > 581 nm < 0 no current at all. False
D: Blue light ( 450–490 nm) > 0 current flows. True
E: White light contains violet, blue, green and yellow components with > 0 current flows. True
A, B, D and E.
Answer: (3)