If the de Broglie wavelength of a particle of mass $\mathrm{m}$ is $100$ times its velocity, then its value in terms of its mass ($\mathrm{m}$) and Planck's constant ($\mathrm{h}$) is

An electron and a photon each have a wavelength of 1.00 nm. Find their momenta.

Find the

(a) maximum frequency, and

(b) minimum wavelength of $\mathrm{X}-$rays produced by $30 \mathrm{kV}$ electrons.