The work function of a certain metal is 2.3 , | vedclass

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Question

(B) The work function $W_0 = 2.3 \,eV$. The wave number $\bar{
u} = 2 	imes 10^6 \,m^{-1}$. The energy of the incident photon is $E = hc\bar{
u}$.

Vedclass · Accepted Answer

$0.18 \,eV, 0$

Vedclass · Answer

(B) The work function $W_0 = 2.3 \,eV$. The wave number $\bar{
u} = 2 	imes 10^6 \,m^{-1}$. The energy of the incident photon is $E = hc\bar{
u}$. Using $h = 6.63 	imes 10^{-34} \,J \cdot s$,$c = 3 	imes 10^8 \,m/s$,and $1 \,eV = 1.6 	imes 10^{-19} \,J$: $E = (6.63 	imes 10^{-34}) 	imes (3 	imes 10^8) 	imes (2 	imes 10^6) \,J = 3.978 	imes 10^{-19} \,J$. Converting to $eV$: $E = \frac{3.978 	imes 10^{-19}}{1.6 	imes 10^{-19}} \approx 2.486 \,eV$. According to Einstein's photoelectric equation,$K.E_{\max} = E - W_0 = 2.486 \,eV - 2.3 \,eV = 0.186 \,eV \approx 0.18 \,eV$. The fastest electron has kinetic energy $K.E_{\max} = 0.18 \,eV$. The slowest ejected electron has kinetic energy $0$ (as it just overcomes the work function). Thus,the kinetic energies are $0.18 \,eV$ and $0$.

The work function of a certain metal is $2.3 \,eV$. If light of wave number $2 \times 10^6 \,m^{-1}$ falls on it,the kinetic energies of the fastest and slowest ejected electrons will be respectively:

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