JEE Main 2014 · 11 Apr · Shift 1 · Chemistry Q31

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ChemistrySingle correct+4 / -1Question 31 of 90

If $\lambda_o$ and $\lambda$ be the threshold wavelength and wavelength of incident light, the velocity of photoelectron ejected from the metal surface is :

\sqrt{\dfrac{2h}m(\lambda_o-\lambda)}

\sqrt{\dfrac{2hc}m(\lambda_o-\lambda)}

\sqrt{\dfrac{2hc}m\left(\dfrac{\lambda_o-\lambda}{\lambda\lambda_o}\right)}

\sqrt{\dfrac{2h}m\left(\dfrac1{\lambda_o}-\dfrac1\lambda\right)}

Answer and worked solution

Official answer: C

$\tfrac12mv^2=hc\left(\frac1\lambda-\frac1{\lambda_o}\right)=hc\frac{\lambda_o-\lambda}{\lambda\lambda_o}\implies v=\sqrt{\frac{2hc}m\left(\frac{\lambda_o-\lambda}{\lambda\lambda_o}\right)}.$

Topics:Photoelectric effect and spectra

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JEE Main 2014 · 11 Apr · Shift 1, Chemistry question 31