Electric current is the rate of charge
flow, that passes through a given
point in an electric conductor.
I=Q/t
I= Electric Current (Amperes)
Q= charge (Coulombs)
t= time (Secongs)
Current density
Current density is the electric current per unit
area of cross section
J= I/A = nqvD
Current density (Ampere/m^2)
I= Current (Amperes)
A= Conductor cross
section area (m^2)
n= Number of
particles (#
particles/m^3)
q= charge (Coulombs)
Direct Current
It is the one in which the electric
charge or electrons flow always to
the same direction in a closed
electric circuit
Annotations:
Moving from the negative pole to the positive pole of an electromotive force (EMF). Such as in the batteries, dynamos or any other source that generates this type of electric current.
Alternating Current
It is the electric current in which
both, magnitude and direction, vary
cyclically
Annotations:
Sinusoid wave is the most common form of alternating current, but there are also other periodic waves, such as the triangular or square wave.
The main characteristic of alternating current is that one pole is negative and the other is positive, then an instant later, they invert their polarity; the change in polarity will depend on the frequency of the alternating current, which is measured as the number of cycles per second or Hertz (Hz).