Question

Which particle among the following will have the smallest de-Broglie wavelength, assuming that they have the same velocity?

• A. A positron
• B. A photon
• C. An $\alpha$ particle
• D. A neutron

Answer 1

Answer: (C)

An $\alpha$ particle

The de-Broglie equation is $\lambda =\frac{h}{p}=\frac{h}{mv}$, Here, $h$ and $v$ are constant.

So, $\lambda \propto \frac{1}{m}$. Since, the $-\alpha$ particle has the highest mass among the given entities, it has the smallest de-Broglie wavelegth.