Question

When a beam of accelerated electrons strikes a target, then continuous spectrum of X-rays is obtained. The wavelength absent from the spectrum of X-rays emitted by an X-ray tube operated at 40 KV will be

• A. $1.5\mathring{A}$
• B. $0.5\mathring{A}$
• C. $0.25\mathring{A}$
• D. $1.0\mathring{A}$

Answer 1

Answer: (C)

$0.25\mathring{A}$

Energy of an electron excited by $40KV$ is
$E=40KV\left(e\right)$
This is equated to energy of the radiation.

$E=\frac{hc}{\lambda }$

or $\lambda =\frac{hc}{E}$

Solving we get $\lambda \approx 0.25A^o$