The wavelength of `k_(alpha) ` X- rays produced by an X - rays tube is `0.76 Å` . The atomic number of the anode material of the tube is …….

Options

A. `82`
B. `41`
C. `20`
D. `10`

Explanation

For `K_(alpha)X-`ray line,
`(1)/(lambda_(alpha))=R(Z-1)^(2)[(1)/(1^(2))-(1)/(2^(2))=R(Z-1)^(2)[1-(1)/(4)]`
`rArr (1)/(lambda_(alpha))=(3)/(4)R(z-1)^(2)`…..(`1`)
With reference to given data,
`lambda_(0)=0.76Å=0.76xx10^(-10)m`
`R=1.097xx10^(7)m`
Putting these values in Eq. (`1`),
`(Z-1)^(2)=(4)/(3)(1)/(0.76xx10^(-10)xx1.097xx10^(7))~=1600`
`rArr Z-1=40rArrZ=41`