The threshold wavelength for photoelectric emission from a material is 5500 Å. Photoelectrons will be emitted, when this material is illuminated with monochromatic radiation from a:
A. 75 W infra-red lamp
B. 10 W infra-red lamp
C. 75 W ultra-violet lamp
D. 10 W ultra-violet lamp Choose the correct answer from the options given below:

Question

G1 Physics · Accepted Answer

Photoelectric emission requires wavelength shorter than the threshold wavelength. Ultraviolet light satisfies λ < 5500 Å, whereas infrared does not. The power affects photocurrent, not the threshold condition. Therefore both ultraviolet lamps C and D can produce emission.