The total energy of an electron in the first excited state of hydrogen is about `-3.4 eV`. Its kinetic energy in this state is:

Options

A. `-3.4eV`
B. `-1.7eV`
C. `1.7eV`
D. `3.4eV`

Explanation

`:'K.E.=1/2|P.E.|`
But potential energy is negative.
So total enerty `=K.E.+P.E.`
`=3.4=1/2P.E.-P.E`
`implies-3.4=(-P.E.)/2`
`impliesK.E.=+3.4eV`
Basically `K.E. =|T.E.|impliesK.E.=1/2|P.E.|`