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
`((Me t a l ,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))`

Answer

4

Explanation

the enrgy associated with incident photon `(hc)/( lambda)`
` rArr E = (6.6 xx 10^(-34) xx 3 xx 10^8)/( 300 xx 10^(-90) J`
` E` in `eV = ( 6.6 xx 10^(-34) xx .3 xx 10^8)/( 300 xx 10^(-9) xx 1.6 xx 10^(-19)) = 4. 16 eV`
So, number fo metal showing phote -electric effects whill be (4) , i, e, Li, na, K, Mg, .