The photoelectric behaviour of K,Li,Mg,and Ag | vedclass

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(B) The energy of the incident photon is calculated as $E = \frac{hc}{\lambda}$.Given $\lambda = 400 \ nm = 400 	imes 10^{-9} \ m$.$E = \frac{6.626 \

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$K$ and $Li$

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(B) The energy of the incident photon is calculated as $E = \frac{hc}{\lambda}$.Given $\lambda = 400 \ nm = 400 	imes 10^{-9} \ m$.$E = \frac{6.626 	imes 10^{-34} \ J \ s 	imes 3 	imes 10^8 \ m \ s^{-1}}{400 	imes 10^{-9} \ m} = 4.97 	imes 10^{-19} \ J$.Converting to $eV$: $E = \frac{4.97 	imes 10^{-19} \ J}{1.6 	imes 10^{-19} \ J \ eV^{-1}} \approx 3.1 \ eV$.Photoelectrons are emitted if the incident photon energy is greater than or equal to the work function of the metal.Based on typical work functions ($K \approx 2.2 \ eV$,$Li \approx 2.4 \ eV$,$Mg \approx 3.7 \ eV$,$Ag \approx 4.3 \ eV$),only $K$ and $Li$ have work functions less than $3.1 \ eV$.

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