Question

The minimum wavelength of X-rays produced in an X-ray tube is $\lambda$ when the operating voltage is V. What is the minimum wavelength of the X-rays when the operating voltage is $\frac{V}{2}$?

• A. $\frac{\lambda }{2}$
• B. $\lambda$
• C. $2\lambda$
• D. $4\lambda$

Answer 1

The correct option is C

$2\lambda$

We know that, ${\lambda }_{min}=\frac{hc}{eV}\Rightarrow {\lambda }_{min}\propto \frac{1}{V}$
$\therefore$ The wavelength in the second case is $2\lambda$ and the correct choice is (c).