A $50$ keV x$-$ray interacts photoelectrically with $($a$)$ a carbon atom and $($b$)$ a barium atom.

What is the kinetic energy of each photoelectron.

What is the energy of each characterstic $x-$ray if an $L$ to $K$ transition occur. $($given: for carbon : K$-$shell electorn binding energy $0\mathrm{.}3$ keV $,$ L$-$shell electorn binding energy $0\mathrm{.}006$ keV $.$

for barium : K$-$shell electorn binding energy $37$ keV $,$ L$-$shell electorn binding energy $5\mathrm{.}9$ keV $)$