The constant `'a'` Mosely's law `sqrt(v) - a(Z-b)` for `k_(alpha)X-`rays is related to Rydberg constant R as (`'c'` is the speed of light)

Options

A. `R = (4a^(2))/(3c)`
B. `R = (3c)/(4a)`
C. `R = (3c^(2))/(4)`
D. `R = (2c)/(a)`

Answer

A

Explanation

`(1)/(lambda)=R((1)/(n_(1))-(1)/(n_(2)))Z^(2)`
`(c')/(lambda) = RC((1)/(n_(1))-(1)/(2^(2)))Z^(2)`
For `K_(alpha) rArr v =RC ((1)/(1^(2)) - (1)/(2^(2))) Z^(2)`
`rArr v=(3Rc)/(4)Z^(2)"……"(1)`
& `sqrt(v) = a(z-b)`
`v = a^(2)(z-b)^(2)"……."(2)`
Comparing (1) & (2)
`a^(2) = (3Rc)/(4) rArr R = (4a^(2))/(3c)`