The Davisson and Germer experiment showed that:

The atomic masses of helium and neon are $4.0$ and $20.0 \ amu$ respectively. The value of the de Broglie wavelength of helium gas at $-73^{\circ} C$ is $M$ times the de Broglie wavelength of neon at $727^{\circ} C$. The value of $M$ is

How fast is an electron moving if it has a wavelength equal to the distance it travels in one second?

The wavelength of the electron emitted by a metal sheet of work function $4 \ eV$ when photons from $EMR$ of wavelength $124 \ nm$ strike the metal plate is ........... $nm$.

The wavelength of the electron in the ground state of a hydrogen atom is $y \ \mathring{A}$. What is the wavelength of the electron in the fourth orbit of $He^{+}$ ion (in $\mathring{A}$)?

Calculate the de-Broglie wavelength of an electron travelling at $1\%$ of the speed of light.