In the Bohr's orbit, what is the ratio of total kinetic energy and total energy of the electron

Options

A. `-2`
B. `-1`
C. `+2`
D. `0`

Answer

B

Explanation

K.E. = `1/2 mv^2, P.E. = - (Ze^2)/r`
and electrostatic force = centrifugal force
`(Ze^2)/(r^2) = (mv^2)/r`
or `(Ze^2)/(r ) = mv^2`
or `PE = -mv^2`
`:. ` Total energy ` = 1/2 mv^2 + (-mv^2) = -1/2 mv^2`
`:. ("K.E.")/("Total energy") = (1/2 mv^2)/(-1/2 mv^2) = -1`