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Question
Frequencies of Kα X-rays of different materials are measured. Which one of the graphs in the figure may represent the relation between the frequency v and the atomic number Z ?
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Solution
Using Moseley's Law,
`sqrt(v) = a(Z - b)`,
where v = frequency of Kα X-ray
Z = atomic number
`therefore v = a^2(Z - b)^2`
⇒ `(Z - b)^2 = v/a^2`
This is the equation of a parabola with some intercept on the axis, representing atomic number (Z). Hence, curve d represent this relation correctly.
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