Question

The de-Broglie wavelength of a neutron in thermal equilibrium with heavy water at a temperature $T$ (Kelvin) and mass $m$, is :

• A. $\frac{h}{\sqrt{3m kT}}$
• B. $\frac{2h}{\sqrt{3m kT}}$
• C. $\frac{2h}{\sqrt{m kT}}$
• D. $\frac{h}{\sqrt{m kT}}$

Answer 1

Answer: (A)

$\frac{h}{\sqrt{3m kT}}$

Answer 2

de-Broglie wavelength
$\lambda =\frac{h}{m v}$
$=\frac{h}{\sqrt{2 m( KE )}}$
$=\frac{h}{\sqrt{2 m\left(\frac{3}{2} k T\right)}}$
$\lambda =\frac{h}{\sqrt{3 m k T}}$