Question

$20\, kV$ potential is applied across $X$-ray tube, the minimum wavelength of $X$-ray emitted will be

• A. $0.62\,?$
• B. $0.37\,?$
• C. $1.62\,?$
• D. $1.31\,?$

Answer 1

Answer: (A)

$0.62\,?$

Answer 2

From relation, $\frac{h c}{\lambda_{\min }}=e V$
or $\lambda_{\min } =\frac{h c}{e V}$
or $\lambda_{\min }= \frac{6.6 \times 10^{-34} \times 3 \times 10^{8}}{1.6 \times 10^{-19} \times 20 \times 10^{3}}$
$=0.62 \times 10^{-10} m =0.62\, ?$