The wavelength of `K_(alpha)` line in copper is `1.54 Å`. The ionisation energy of `K` electron in copper in Joule is

Explanation

For `K_(alpha)`-line we can write,
`(1)/(lambda)=R(Z-1)^(2)((1)/(1^(2))-(1)/(2^(2)))=R(Z-1)^(2)xx(3)/(4)rArrR(Z-1)^(2)=(4)/(3lambda_(alpha))`
Ionisation energy of given by
`E=Rhc(Z-1)^(2)((1)/(1^(2))-(1)/(oo))=hc(4)/(3lambda_(alpha))`
`=(6.6xx10^(-34)xx3xx10^(8)xx4)/(3xx1.54xx10^(-10))=1.7xx10^(-15)J`