I is the flow of electrons in amperes current flows from the point of highest potential (negative) to the point of lowest potential (positive) 

R is resistance to the flow of current in ohms. 

Z is impedance to the flow of alternating current in ohms. 

P is electrical power to do work in watts 

I=E/Z Z=E/I E=I*Z 

P=E*I 

P=E**2/R(or Z) 

P=I**2*R(or Z) 

E = P/I 

I*R 

I*Z  square root of (P*R) 

square root of (P*Z) 

I = P/E 

E/R 

E/Z 

square root of (P/R) 

square root of (P/Z) 

R = E/I Z = E/I P/I**2 P/I**2 E**2/P E**2/P P = E*I R*(I**2) Z*(I**2) 

E**2/R 

E**2/Z