An X-ray tube with a copper target is found to be emiting lines other than those due to copper. The `K_(alpha)` line of coper is known to have a wavelength `1.5405 Å` and the other two `K_(alpha)` lines observed have wavelengths `0.7090 Å and 1.6578 Å` Identify the impurities.

Explanation

According to Meseley's equation for `K_(alpha)` radiation,
`(1)/(lambda) = R (Z - 1)^(2) [(1)/(1^(2)) - (1)/(2^(2))]` `(lambda =` wevelength corresponding to `Cu)`
Let `lambda _(1) and lambda _(2)` be the two other unknown , than
`(lambda _(1))/(lambda) = ((Z - 1)^(2))/(Z_(1) - 1)^(2) = (0.7092)/(1.5405)`
For copper , `Z = 29`, therefore,
`(Z_(1) - 1) = 28 sqrt((1.5405)/(0.7092)) = 41`
or `Z_(1) = 42` (Molybdenum)
Similarly, `(lambda _(2))/(lambda) = ((28)^(2))/((Z_(2) - 1)^(2)) = (1.6578)/(1.5405)`
`(Z_(1) - 1) = 28 sqrt(((1.5405)/(1.6578)))`
or `Z_(2) - 1) = 27 or Z_(2) = 28 (Nickel)`
So the impurities are molybdenum and nickel.