If `epsilon_(0)` be the permittivity of vacuum and r be the radius of orbit of H- atom in which electron is revolving, then velocity of electron is given by :

Options

A. `(e)/sqrt(4pimepsilon_(0)r)`
B. `(2e)/sqrt(pimepsilon_(0)r)`
C. `(e)/sqrt(pimepsilon_(0)r)`
D. `(e)/sqrt(4pimepsilon_(0)r)`

Answer

A

Explanation

`(mv^(2))/r=1/(4piin_(0)) xx e^(2)/r^(2)`
`v = e/sqrt(4piin_(0)rm)`