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12.Atoms
normal
An electron having de-Broglie wavelength $\lambda$ is incident on a target in a X-ray tube. Cut-off wavelength of emitted $X$-ray is :
A
$0$
B
$\frac{h c}{m c}$
C
$\frac{2 m^{2} c^{2} \lambda^{2}}{h^{2}}$
D
$\frac{2 m c \lambda^{2}}{h}$
Solution
$\lambda=\frac{{h}}{{mv}}$
Kinetic energy, $\frac{{P}^{2}}{2 {m}}=\frac{{h}^{2}}{2 {m} \lambda^{2}}=\frac{{hc}}{\lambda_{{c}}}$
$\lambda_{c}=\frac{2 m \lambda^{2} c}{h}$
Standard 12
Physics
