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(A) The energy of the incident photon is given by $E = \frac{hc}{\lambda}$.Using $h = 6.626 	imes 10^{-34} \ J \cdot s$,$c = 3 	imes 10^8 \ m/s$,and

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$4$

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(A) The energy of the incident photon is given by $E = \frac{hc}{\lambda}$.Using $h = 6.626 	imes 10^{-34} \ J \cdot s$,$c = 3 	imes 10^8 \ m/s$,and $\lambda = 300 	imes 10^{-9} \ m$:$E = \frac{6.626 	imes 10^{-34} 	imes 3 	imes 10^8}{300 	imes 10^{-9}} \ J = 6.626 	imes 10^{-19} \ J$.Converting to $eV$ by dividing by $1.602 	imes 10^{-19} \ J/eV$:$E = \frac{6.626 	imes 10^{-19}}{1.602 	imes 10^{-19}} \approx 4.136 \ eV$.Photoelectric effect occurs if the work function $\phi Comparing the given values: $Li \ (2.4)$,$Na \ (2.3)$,$K \ (2.2)$,and $Mg \ (3.7)$ are all less than $4.136 \ eV$.Therefore,there are $4$ such metals.

Metal	$Li, Na, K, Mg, Cu, Ag, Fe, Pt, W$
$\phi \ (eV)$	$2.4, 2.3, 2.2, 3.7, 4.8, 4.3, 4.7, 6.3, 4.75$

The work function $(\phi)$ of some metals is listed below. The number of metals which will show photoelectric effect when light of $300 \ nm$ wavelength falls on the metal is

Metal $Li, Na, K, Mg, Cu, Ag, Fe, Pt, W$

$\phi \ (eV)$ $2.4, 2.3, 2.2, 3.7, 4.8, 4.3, 4.7, 6.3, 4.75$

Similar Questions

Work functions of four metals $M_1, M_2, M_3$ and $M_4$ are $4.8, 4.3, 4.75$ and $3.75 \ eV$ respectively. The metals which do not show photoelectric effect when light of wavelength $310 \ nm$ falls on the metals are

Linear spectrum (line spectrum) is a characteristic of which of the following?

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The work function $(\phi)$ of some metals is listed below. The number of metals which will show photoelectric effect when light of $300 \ nm$ wavelength falls on the metal is Metal $Li, Na, K, Mg, Cu, Ag, Fe, Pt, W$ $\phi \ (eV)$ $2.4, 2.3, 2.2, 3.7, 4.8, 4.3, 4.7, 6.3, 4.75$