1. Current Density and Current Conservation*

1.3

Current Conservation

The equation of continuity for conservation of electric is derived. An expression for current in a wire is obtained in terms of number of electrons per unit volume.
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1.4

Local Conservation of Charge

The meaning of charge conservation is discussed. It is known to be mathematically represented by  the equation of continuity. It is argued that special relativity requires that there should be  a n equation of continuity, and  that there should be a Lorentz four vector current  associated with  every conservation law.