Time taken by an electrons to complete one revolution in the Bohr orbit of the `H` atom is

Options

A. `(4pi^(2) mr^(2))/(nh)`
B. `(nh)/(4pi^(2) mr)`
C. `(2pi mr)/(pi^(2) h^(2))`
D. `(h)/(2pi mr)`

Answer

A

Explanation

Time taken to complete one revolution.
`t = ("Circumference")/("Velocity")`
`t = (2pi r)/(v)`
Now `m v r = (nh)/(2pi)`
`:. v = (nh)/(2pi mr)`
Substituting the value of v, we get
`t = (2pi r. 2pi m r)/(nh) =(4pi^(2) m r^(2))/(nh)`