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

When light of wavelength $248 \, nm$ falls on a metal of threshold energy $3.0 \, eV$,the de-Broglie wavelength of emitted electrons is ............. $\mathring{A}$ (Round off to the Nearest Integer). [Use : $\sqrt{3}=1.73, h =6.63 \times 10^{-34} \, Js, m_e =9.1 \times 10^{-31} \, kg, c =3.0 \times 10^{8} \, ms^{-1}, 1 \, eV =1.6 \times 10^{-19} \, J$]

The mass of a proton is $1.67 \times 10^{-27} \ kg$. If it is moving with a velocity of $10^3 \ m/s$,calculate its wavelength in nanometers.

The velocity of a de Broglie wave is represented by which of the following expressions?

What is the de-Broglie wavelength of an electron,in a hydrogen atom,moving in an orbit having a maximum magnetic quantum number $m = +2$ in units of $\mathring{A}$?

$A$ ball weighing $25 \ g$ moves with a velocity of $6.6 \times 10^4 \ cm/sec$. Find the associated de Broglie wavelength.