  A electron of mass $m$, when electrically scatters of nucleus, of mass $M$,
transfers momentum $q$ to the nucleus. The energy lost by electron is more than
the energy gained by the nucleus. The resulting energy goes in exciting the
atom to a higher energy state as in Frank Hertz experiment and sodium, neon,
mercury vapor lamps, or ionization of atom as in bubble and cloud chamber
experiments, or just production of X-rays as in Bremsstraulung. In this paper,
we study these phenomenon. These experiments are inelastic scattering
experiments. We remark, why neutrinos donot scatter and can penetrate earth,
why muons travel further than electrons in materials and why a material like
lead plate can slow down electrons and positrons efficiently. We look at the
elastic scattering of electrons as in electron diffraction and electron
microscopes. We look at scattering of electrons in the condensed matter, these
phenomenon range from scattering of electrons of periodic potential, to give
Bloch waves, scattering of electrons of phonons and impurities to give
resistance, scattering of electrons of lattice to give cooper pairs and
superconductivity. We study electron scattering from exchange potential as in
Fermi liquid theory and resulting $T^2$ resistance at low temperatures.
Electron scattering of exchange potential resulting in chemical reactions. We
turn our attention to electron-proton scattering both eleastic and inelastic,
as in deep inelastic scattering experiments and understand the independence of
ineleastic cross-section of with respect to transferred momentum. We see, why
we can just say that there are three quarks in proton from elastic
cross-section. Our main contribution in this article is we are detailed at
places, we find literature terse.
