MCQ
The graph which shows the variation of $\left(\frac{1}{\lambda^2}\right)$ and its kinetic energy, $E$ is (where $\lambda$ is de Broglie wavelength of a free particle):
  • A

  • B


  • D

Answer

Correct option: C.

c
de-Broglie wavelength $\lambda=\frac{h}{P}=\frac{h}{m v}=\frac{h}{\sqrt{2 m E}}$ where $E=\frac{1}{2} m v^2$

Squaring both sides,

$\lambda^2=\frac{h^2}{4 m^2 E}$

$\Rightarrow \frac{1}{\lambda^2}=\text { (constant) } E$

Graph passes through origin with constant slope.

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