Question

The intensity 1 of X-rays from the 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:

• A. ${\lambda }_K-{\lambda }_C$ increases
• B. ${\lambda }_K-{\lambda }_C$ decreases
• C. ${\lambda }_k+{\lambda }_c$ Increase
• D. None of these

Answer 1

Answer: (A)

${\lambda }_K-{\lambda }_C$ increases

Wavelength ${\lambda }_k$ is independent of the accelerating voltage $\left(V\right)$, while the minimum wavelength ${\lambda }_C$, is inversely proportional to $V$.

Therefore as $V$ increases, ${\lambda }_k$ remains unchanged where as ${\lambda }_C$ decreases of ${\lambda }_k-{\lambda }_C$ will increases.