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. `-6.8eV`
C. `6.8 eV`
D. `3.4 eV`

Answer

d

Explanation

We have ,Kinetic energy of electron,
`K=(Ze^(2))/(8piepsilon_(0)*r)`
also ,Potential energy of electron
`U=-(1)/(4piepsilon_(0))*(Ze^(2))/(R )` `therefore` Total enery
`E=K+U`
`=(Ze^(2))/(8piepsilon_(0)*r)-(Ze^(2))/(4piepsilon_(0)*r)`
`E=-(Ze^(2))/(8piepsilon_(0)r)orK=-E=-(-3.4)`
`=3.4eV` .