An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius `r`. The coulomb force `vec(F)` between the two is (where `k=(1)/(4piepsilon_(0)))`

Options

A. `-k e^2/r^3 hatr`
B. `k e^2/r^3 vecr`
C. `-k e^2/r^3 vecr`
D. `k e^2/r^2 hatr`

Answer

C

Explanation

Charge in the nucleus of hydrogen is +e and the charge of electron is -e .The direction of electric force on electron will be towards the centre of nucleus.
`F=1/(4piepsilon_0)(q_1q_2)/r^2 rArr vecF=-k e^2/r^2 hatr`
`rArr vecF=-k e^2/r^3 vecr`