Question

By making applied voltage one fourth of the initial value in X- ray tube, cut-off wavelength for the continuous X- ray becomes

• A. four times
• B. one fourth times
• C. two times
• D. sixteen times

Answer 1

The correct option is A four times

The cutoff wavelength in terms of applied voltage for X-rays is given by,

$\lambda =\frac{1240\text{eV nm}}{eV}$

$\Rightarrow \lambda \propto \frac{1}{V}$

Given, $V_2=\frac{1}{4}{V}_1$

So, we get,

$\frac{{\lambda }_1}{{\lambda }_2}=\frac{V_2}{V_1}$

$\frac{{\lambda }_1}{{\lambda }_2}=\frac{\frac{1}{4}{V}_1}{V_1}$

$\therefore {\lambda }_2=4{\lambda }_1$

Hence, option $\left(\text{A}\right)$ is correct.