Dual Nature of Matter

JEE Main level, single correct, medium

161 of 200

Question 161 of 200

The stopping potential for electrons emitted from a photosensitive surface illuminated by light of wavelength 491nm491nm is 0.710V.0.710V. When the incident wavelength is changed to a new value, the stopping potential is 1.43V.1.43V. The new wavelength is :

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Answer: (A) 382nm382nm

hcλ=ϕ+eVs\dfrac{hc}{\lambda }=\phi +e{V}_{s}
1240491=ϕ+0.71...(1)\dfrac{1240}{491}=\phi +0.71...\left(1\right)
1240λ=ϕ+1.43...(2)\dfrac{1240}{\lambda }=\phi +1.43...\left(2\right)
∴λ=382nm∴\lambda =382nm

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