Modern Physics Ques 88
- The threshold wavelength for photoelectric emission from a material is $5200 $ $\AA$. Photoelectrons will be emitted when this material is illuminated with monochromatic radiation from a
(1982, 3M)
(a) $50 $ $W$ infrared lamp
(c) $50 $ $W$ ultraviolet lamp
(b) $1 $ $W$ infrared lamp
(d) $1 $ $W$ ultraviolet lamp
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Answer:
Correct Answer: 88.(c,d)
Solution:
Formula:
- For photoemission to take place, wavelength of incident light should be less than the threshold wavelength. Wavelength of ultraviolet light $<5200 $ $\AA$ while that of infrared radiation > $5200 $ $\AA$.
BETA
