A radiation of 2000Å falls on the metal whose work function is 4.2 eV. Then the kinetic energy of the fastest photo eletron is

A radiation of 2000Å falls on the metal whose work function is 4.2 eV

1.	A radiation of 2000Å falls on the metal whose work function is 4.2 eV. Then the kinetic energy of the fastest photo eletron is
Answer» `6.4xx10^(-10)` J `16xx10^(-10)` J `1.6xx10^(-19)` J `3.2xx10^(-19)` J Solution :Kinetic energy (KE) `=hv-W` `(HC)/lambda-4.2eV(6.62xx10^(-34)xx3xx10^(8))/(2000xx10^(-10))=-4.2xx1.6xx10^(-19)` `=9.9xx10^(-19)j-6.7xx10^(-19)J=3.2xx10^(-19)` J