Question

The minimum wavelength of X-ray emitted by X-ray tube is $0.4125A$. The accelerating voltage is

• A. $30kV$
• B. $50kV$
• C. $80kV$
• D. $60kV$

Answer 1

The correct option is A $30kV$

Wavelength of X-ray, $\lambda =0.4125A=0.4125\times {10}^{-10}m$
For minimum wavelength we know that:
$eV=\frac{hc}{\lambda }$
$\therefore V=\frac{hc}{e\lambda }=\frac{6.6\times {10}^{-34}\times 3\times {10}^8}{1.6\times {10}^{-19}\times 0.4125\times {10}^{-10}}=3\times {10}^{4}V=30kV$