Modern Physics 2 Question 26
25. 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
Integer Answer Type Questions
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Solution:
- 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 > $5200 \AA$.
