A photon of wavelength ` 4 xx 10^(-7) m` strikes on metal surface , the work function fo the metal being ` 2. 13 eV` Calculate :
(i) the energy of the photon (ev)
(ii) the kinetic energy fo the emission and
the velocity fo the photoelectron `( 1 eV = 1 , 6020 xx 10^(-19) J)`,

Explanation

Energy `(E)=(hc)/lambda=(6.6xx10^(-34)J sxx3xx10^(8) ms^(-1))/(4xx10^(-7)m)`
`=4.97xx10^(-19) J=3.10 eV`
b. `lambda=4xx10^(-7)m`
`W_(0)=2.13 eV`
`(KE=hv-W_(0)) or (hv=hv_(0)+KE)`
`KE=(hc)/lambda-W_(0)=3.10 eV-2.13 eV`
`KE=0.97 eV =0.97xx1.6xx10^(-19) J`
c. `KE=1/2mv^(2)=0.97xx1.6xx10^(-19)J`
`=1/2xx9.1xx10^(-31) kgxxv^(2)=0.97xx1.6xx10^(-19)J`
`v=5.8xx10^(5) m s^(-1)`