JEE MAIN - Physics (2023 - 29th January Morning Shift - No. 16)
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 :
C only
A and D only
C and D only
B and C only
Explanation
Wavelength of infra-red $=700 \mathrm{~nm}$ (minimum)
Wavelength of UV $=100-400 \mathrm{~nm}$
Since we need $\lambda<5000$ Å
$\Rightarrow$ Only UV would be able to emit photoelectrons.
Wavelength of UV $=100-400 \mathrm{~nm}$
Since we need $\lambda<5000$ Å
$\Rightarrow$ Only UV would be able to emit photoelectrons.
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