Question

The operating voltage is increased by 2%. By what % cut off wavelength of X-ray decrease in a Coolidge tube

• A. 1 %
• B. 1.5 %
• C. 1.8 %
• D. 2 %

Answer 1

The correct option is D 2 %

$\lambda =\frac{1240\ast {10}^{-9}}{V}$ or $\frac{d\lambda }{\lambda }=-\frac{dV}{V}=2$%

So, the answer is option (D).