Ultraviolet radiations of 6.2 eV fall on an aluminium surface (work function 4.2 eV ) . The kinetic energy (in joule ) of the fastest electron emitted is approximately

Options

A. `3.2 xx10^(-21)`
B. `3.2 xx10^(-19)`
C. `3.2 xx10^(-17)`
D. `3.2 xx10^(-15)`

Answer

B

Explanation

`K_("max") = hv - phi_0 implies K_("max")= (6.2 -4.2)eV =2eV`
`=2xx1.6 xx10^(-19)J = 3.2 xx10^(-19) J`