The wavlength of `K_(alpha),` X-rays produced by an X-ray tube 0.76Å . The atomic number of the anode material of the tube is

Options

A. 30
B. 40
C. 50
D. 60

Answer

B

Explanation

`(1)/(lambda) = Z^(2) R_(oo) ((1)/(n_(1)^(2)) - (1)/(n_(2)^(2)))`
for `K_(alpha) line , n_(1) = 1 and n_(2) = 2`
`(1)/(lambda) = Z^(2) R_(oo) (3)/(4)`
`Z = sqrt((4)/(3lambda R_(oo))) = 39.9 = 40`