Liquid helium is used to cool Jefferson Lab's accelerator components.
stone
Conductors.
resistance
Tungsten. Gold or uranium may also be used but it is usually tungsten.
stone
Orbital and spin motion of electron
A ballistic electron travels a straight course through a semiconductor without scattering off any atoms. In other words it travels through a material as if the material had no atoms in it.
because values of charge and mass of electron remains constant whatever may be the material.
Atoms are not added but rather the material (usually silicon) is doped with an impurity like germanium to either add an extra electron (n-material) or be missing an electron (p-material) in the outer valance shell.
ohms law (resistance)
An electron ejected from the surface of a material by the photoelectric effect
http://en.wikipedia.org/wiki/Thomas_Jefferson