Modern Physics 4 Question 13
13. $K _{\alpha}$ wavelength emitted by an atom of atomic number $Z=11$ is $\lambda$. Find the atomic number for an atom that emits $K _{\alpha}$ radiation with wavelength $4 \lambda$
(a) $Z=6$
(b) $Z=4$
(c) $Z=11$
(d) $Z=44$
$(2005,2 M)$
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Solution:
- $\quad \frac{1}{\lambda} \propto(Z-1)^{2}$
$$ \therefore \quad \frac{\lambda _1}{\lambda _2}={\frac{Z _2-1}{Z _1-1}}^{2} \text { or } \frac{1}{4}={\frac{Z _2-1}{11-1}}^{2} $$
Solving this, we get $Z _2=6$
