The threshold wavelength for photoelectric emission from a material is 5500 $\mathop A\limits^o$. 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 :
Solution
Wavelength of infra-red $=700 \mathrm{~nm}$ (minimum)
<br/><br/>
Wavelength of UV $=100-400 \mathrm{~nm}$
<br/><br/>
Since we need $\lambda<5000$ Å
<br/><br/>
$\Rightarrow$ Only UV would be able to emit photoelectrons.
About this question
Subject: Physics · Chapter: Dual Nature of Matter and Radiation · Topic: Photoelectric Effect
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