What is energy of a photoelectron, in electronvolt, moving with a velocity of `2 xx 10^(7) m s^(-1)`? (Given, mass of electron `= 9.1 xx 10^(-28)g`)

Explanation

Mass of electron `= 9.1 xx 10^(-28) g = 9.1 xx 10^(-31) kg` Kinetic energy of the electron
`= (1)/(2) mv^(2) = (1)/(2) xx (9.1 xx 10^(-31)) xx (2 xx 10^(7))^(2)J`
`= (1)/(2) xx {(9.1 xx 10^(-31) xx (2 xx 10^(7))^(2))/(1.6 xx 10^(-19))} eV = 1137.5 eV`