Find the de-Broglie wavelength of an electron with kinetic energy of $ 120 eV $. (in $pm$)

$A$ photon and an electron (mass $m$) have the same energy $E$. The ratio $\left(\frac{\lambda_{\text{photon}}}{\lambda_{\text{electron}}}\right)$ of their de Broglie wavelengths is: ($c$ is the speed of light)

Find the typical de Broglie wavelength associated with a $He$ atom in helium gas at room temperature $(27^{\circ}C)$ and $1 \; atm$ pressure; and compare it with the mean separation between two atoms under these conditions.

The de Broglie wavelength for a deuteron can be given by:

An electron microscope uses which property of the electron?

If the kinetic energy of a free electron is doubled,its de Broglie wavelength becomes ........... times.