Dual Nature of Matter

JEE Main level, single correct, medium

151 of 200

Question 151 of 200

A monochromatic neon lamp with wavelength of 670.5nm670.5nm illuminates a photo-sensitive material which has a stopping voltage of 0.48V0.48V. What will be the stopping voltage if the source light is changed with another source of wavelength of 474.6nm474.6nm ?

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Answer: (C) 1.25V1.25V

eVs=hcλ−ϕ{eV}_{s}=\dfrac{hc}{\lambda }-\phi
e(V′−V)=hc(1λ′−1λ)e\left({V}^{'}-V\right)=hc\left(\dfrac{1}{{\lambda }^{'}}-\dfrac{1}{\lambda }\right)
V′=hce(1λ′−1λ)+V{V}^{'}=\dfrac{hc}{e}\left(\dfrac{1}{{\lambda }^{'}}-\dfrac{1}{\lambda }\right)+V
=1240(1474−1670)+0.48=1.25eV=1240\left(\dfrac{1}{474}-\dfrac{1}{670}\right)+0.48=1.25eV

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