Question

Hard X-rays for the study of fractures in bones should have a minimum wavelength of ${10}^{-11}$ m. The accelerating voltage for electrons in X-ray machine should be

• A. <124.2 kV
• B. >124.2 kV
• C. between 60 kV and 70 kV
• D. = 100 kV

Answer 1

The correct option is B

>124.2 kV

${\lambda }_{min}=\frac{hc}{eV}=\frac{1.242\times {10}^{-6}}{V}$

or $V=\frac{1.242\times {10}^{-6}}{{10}^{-11}}$

$=124.2\times {10}^{3}V$

$=124.2kV$