Question
Question: The threshold wavelength for photoelectric emission from a material is 5200 Å. Photo-electrons will ...
The threshold wavelength for photoelectric emission from a material is 5200 Å. Photo-electrons will be emitted when this material is illuminated with monochromatic radiation from a -
A
50 watt infrared lamp
B
1 watt infrared lamp
C
50 watt ultraviolet
D
Both (2) and (3)
Answer
50 watt ultraviolet
Explanation
Solution
l0 = 5200 Å [visible range]
l £ l0 [for photo electron emission]
l £ visible range
