Current Electricity
The branch of physics
deals with the study of motion of electric charges is called
current electricity. In an charged metallic conductor at rest, some (not
all) electrons are continually moving randomly through the conductor because
they are very loosely attached to the nuclei. The thermodynamic internal energy
of the materials sufficient to liberate the outer electrons from individual atoms,enabling
the electrons to travel through the material. But the net flow of charge at any
point is zero. Hence, there is zero current. The external energy necessary to
drive the free electrons in a definite direction is called electromotive force (emf).
The emf is not a force ,but it is the work done in moving a unit charge from
one end to the other. The flow of free electrons in a conductor constitutes
electric current
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