Electrical current is a fundamental property associated with circuits. In this post ElectricalEngineering.XYZ presents all the important formulas you should know about Electric current. You can watch the video below or skip the video and read text if you want.

Contents

- 1 Electric Current Formula By Definition
- 2 Electric Current Formula from Ohm’s Law
- 3 Electric current Formula when Power and Voltage is Known
- 4 Electric current formula from Power and Resistance
- 5 Electric Current Formula in Single Phase AC Circuits
- 6 Electric Current Formula in Three-Phase AC Circuits
- 7 Other Current Formulas

## Electric Current Formula By Definition

By definition electric current is defined as the rate of flow of charge.

1 Ampere is the current in circuit when 1 coulomb of charge passes through a given point in one second.

Mathematically

**I = Q/t**

where

I = current in amps

Q = charge in coulombs

t = time in seconds

## Electric Current Formula from Ohm’s Law

According to Ohm’s law, current is defined as ratio of voltage to resistance.

Mathematically

**I = V/R**

Where

I = current in amps

V = Voltage in volts

R = Resistance in ohms

## Electric current Formula when Power and Voltage is Known

Electric current formula can also be expressed in terms of power and voltage.

**I = P/V**

Where

I = Current

P = Power

V = Voltage

## Electric current formula from Power and Resistance

In case of know power and resistance the electric current formula is:

**I = √(P/R)**

where

I = Current

P = Power

R = Resistance

## Electric Current Formula in Single Phase AC Circuits

In case of single phase AC circuits the current formula is:

**I = P/(V * PF)**

Where

I = current

P = Power

V = Voltage

PF = Power factor (Cosθ)

## Electric Current Formula in Three-Phase AC Circuits

In case of three phase AC circuits the formula for current is:

**I = P/(V * PF * 1.73)**

Where

I = current

P = Power

V = Voltage

PF = Power factor (Cosθ)