Modern Physics 4 Question 16
16. The intensity of $X$-rays from a coolidge tube is plotted against wavelength $\lambda$ as shown in the figure. The minimum wavelength found is $\lambda _c$ and the wavelength of the $K _{\alpha}$ line is $\lambda _k$. As the accelerating voltage is increased
$(2001,2 M)$
(a) $\lambda _k-\lambda _c$ increases
(b) $\lambda _k-\lambda _c$ decreases
(c) $\lambda _k$ increases
(d) $\lambda _k$ decreases
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Solution:
- Wavelength $\lambda _k$ is independent of the accelerating voltage (V), while the minimum wavelength $\lambda _c$ is inversely proportional to $V$. Therefore, as $V$ is increased, $\lambda _k$ remains unchanged whereas $\lambda _c$ decreases or $\lambda _k-\lambda _c$ will increase.
