If the kinetic energy of an electron of mass $9.0 \times 10^{-31} \ kg$ is $2.0 \times 10^{-25} \ J$,the wavelength of the electron in $nm$ is approximately (in $.3$)

The ratio of de-Broglie wavelengths of two particles having mass ratio $1:3$ and kinetic energy ratio $2:1$ is

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.

What is the characteristic of an electron microscope? On which principle is it based?

The ratio of de Broglie wavelengths of two particles,having mass ratio $1 : 3$ and kinetic energy ratio $2 : 1$ is

The wavelength associated with the electron moving in the first orbit of hydrogen atom with velocity $2.2 \times 10^6 \ ms^{-1}$ (in $nm$) is $\left(m_e=9.0 \times 10^{-31} \ kg, h=6.6 \times 10^{-34} \ Js\right)$