ELECTRICAL FORMULA

 

Electrical Current Formulas

Electrical Current Formulas in DC Circuit
I=V/R
I = P/V
I = √P/R

*Where
I = Current in Amperes (A)
V = Voltage in Volts (V)
P = Power in Watts (W)
R = Resistance in Ohm (Ω)

Electrical Current Formulas in Single Phase AC Circuit
I = P / (V x Cosθ)
I=(V/Z) …Where Z = impedance = Resistance of AC Circuits
Electrical Current Formulas in Three Phase AC Circuit
I = P / √3xVxCosθ

Voltage or Electrical Potential Formulas

Electrical Potential or Voltage Formula in DC Circuits
V = I x R
V = P / I
V = √ (P x R)

Voltage or Electrical Potential Formulas in Single Phase AC Circuits
V = P/(IxCosθ)
V = I / Z… Where Z = impedance = Resistance of AC Circuits

Electrical Resistance Formulas
R = V/I
R = P/I2
R = V2/P

Electrical Resistance & Impedance Formulas in AC Circuits
In AC Circuits (Capacitive or inductive Load), Resistance = Impedance i.e., R = Z
Z = √(R2 + XL2)… In case of Inductive Load
Z = √(R2 + XC2)…In case of Capacitive Load
Z = √(R2 + (XL– XC)2…In case of both inductive and capacitive Loads.

*Good to know:
Where;
XL = Inductive reactance
= XL = 2πfL…Where L = Inductance in Henry
And;
Xc = Capacitive reactance
= Xc = 1/2πfC… Where C = Capacitance in Farads.

Electrical Power Formulas

Electrical Power formulas in DC Circuits
P = VxI
P = I2R
P = V2/R

Electrical Power formulas in Single Phase AC Circuits
P = VxI Cosθ
P = I2 x R Cosθ
P = (V2/R) Cosθ

Electrical Power formulas in Three Phase AC Circuits
P =√3 x VLxIL Cosθ
P =3 x VPxIP Cosθ
P =3 I2 x R Cosθ
P =3 (V2/R) x R Cosθ