If the de Broglie wavelength of electron is $728.14 \mathrm{~nm}$, its kinetic energy in $\mathrm{J}$ is: (mass of electron $=9.1 \times 10^{-31} \mathrm{~kg} ; \mathrm{h}=6.626 \times 10^{-34} \mathrm{~J} \mathrm{~s}$)