Q. Among the graphs depicted, which one correctly relates of frequency $\nu$ of a particular characteristic $X$ -ray with the atomic number $Z$ of the material ?

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A

B

C

D

Solution:

From Moseley's law, the frequency of $X$ -rays is $\nu=A.\left(\right.Z-b\left(\left.\right)^{2}$ . To analysis the graph we replace $\nu \rightarrow y,Z \rightarrow x$ . We get $y \propto x^{2}$ . This is the equation of a parabola. And at $Z=b,\nu=0$

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