Generally, the power is defined as the amount of work done per unit. In electrical terms, it can be though as the energy supplied by the current in a certain unit of time.
Four basic formulas can be used to calculate electrical power under different circumstances.
|Formulas to calculate Power|
|General formula||P =
|In terms of voltage and current||P = VI|
|In terms of current and resistance||P = I2R|
|In terms of voltage and resistance||P =
|In terms of velocity||P = F.v|
|In terms of workdone||P =
Power Formula Calculator
Enter energy and time to obtain the power.
Derivation of P = VI
P = W/t … (1)
From the formula of voltage, we know that V = W/Q or alternatively:
W = QV Putting W = QV in equation 1
P = QV/t
Since current can be mathematically expressed as I = Q/t
We can replace it with the formula of Power.
P = V.I .. (2)
Equation 2 is the derivation of power in terms of electrical engineering.
Velocity & Wattage
Power can also be expressed in terms of velocity. P = Fv
Unit of power
Power is measured in terms of watts. One watt itself is the one joule of work done in one second. Mathematically,
1 watt = 1 joule per second
The power of electrical components is often labeled on them. The approximate wattage rating of some electronic devices is mentioned here:
|1 Ton AC||1200|
|1.5 Ton AC||1500|
Other Power formulas
kVA to Amps: A formula used for converting kVA to amps.
Amps to kVA: A formula used for converting amperes to kVA
Amps to kW: A formula used for converting amps to kW in AC, Single, two and three phase dc circuits.
kWh to joules: A formula which is used for converting kilowatt-hours to joules.
Summary of all formulas: