Let ${\mathrm{\lambda }}_{\mathrm{\alpha }},{\mathrm{\lambda }}_{\mathrm{\beta }}\mathrm{and}{\mathrm{\lambda }}_{\mathrm{\alpha }}^{\text{'}}$ denote the wavelengths of the X-rays of the ${\mathrm{K}}_{\mathrm{\alpha }},{\mathrm{K}}_{\mathrm{\beta }}\mathrm{and}{\mathrm{L}}_{\mathrm{\alpha }}$ lines in the characteristic X-rays for a metal

• A

  ${\mathrm{\lambda }}_{\mathrm{\alpha }}>{\mathrm{\lambda }}_{\mathrm{\alpha }}^{\text{'}}>{\mathrm{\lambda }}_{\mathrm{\beta }}$

• B

  ${\mathrm{\lambda }}_{\mathrm{\alpha }}^{\text{'}}>{\mathrm{\lambda }}_{\mathrm{\beta }}>{\mathrm{\lambda }}_{\mathrm{\alpha }}$

• C

  $\frac{1}{{\mathrm{\lambda }}_{\mathrm{\beta }}}=\frac{1}{{\mathrm{\lambda }}_{\mathrm{\alpha }}}+\frac{1}{{\mathrm{\lambda }}_{\mathrm{\alpha }}^{\text{'}}}$

• D

  $\frac{1}{{\mathrm{\lambda }}_{\mathrm{\alpha }}}+\frac{1}{{\mathrm{\lambda }}_{\mathrm{\beta }}}=\frac{1}{{\mathrm{\lambda }}_{\mathrm{\alpha }}^{\text{'}}}$