Question

what is the equation for electric current and how it derived?

Answer 1

electric current =I

so I =W/Q
ELECTRIC CURRENT IS OBTAINED BY THE WORK DONE TO MOVE A ELECTRIC CHARGE IS DEFINED AS ELECTRIC CURRENT

Answer 2

electric current is the amount of charge flowing through a wire of particular cross section in unit time 
so, 
CURRENT=CHARGE/TIME
I=Q/T
OR
According to Ohm's  law,
V=IR
SO, 
I=V/R