The wavelengths of electron waves in two orbits are in the ratio $3: 5$. The ratio of the kinetic energy of the electrons will be:

If $a_0$ is the radius of the first Bohr's orbit of the $H$-atom, the de-Broglie wavelength of an electron revolving in the second Bohr's orbit will be: (in $\pi a_0$)

The de Broglie wavelength associated with a ball of mass $1 \, kg$ having kinetic energy $0.5 \, J$ is

With what velocity must an electron travel,so that its momentum is equal to that of a photon of wavelength $663 \ nm$ (in $m/s$)?

If the kinetic energy of an electron is $1.25 \times 10^{-28} \ J$,then what will be the de-Broglie wavelength of the electron? (Mass of electron $= 9 \times 10^{-31} \ kg$,$h = 6.6 \times 10^{-34} \ Js$)

Which of the following relations is correct, if the wavelength $(\lambda)$ is equal to the distance travelled by the electron in one second? $h$ is the Planck's constant and $m$ is the mass of electron.