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Electrical power is the rate at which electrical energy is transferred or converted. The three equivalent power formulas (P = VI, P = I²R, P = V²/R) allow power to be calculated from any two of the three fundamental quantities (V, I, R). Power is measured in watts (W), where 1 watt = 1 joule per second.

Formula

P = V × I (power = voltage × current)
P
watts × seconds) — watts × seconds)
V
voltage × current) — voltage × current)
I
voltage × current) — voltage × current)

Guida passo passo

  1. 1P = V × I (power = voltage × current)
  2. 2P = I² × R (useful when voltage is unknown)
  3. 3P = V² / R (useful when current is unknown)
  4. 4Energy consumed: E = P × t (joules = watts × seconds)
  5. 5kWh (unit on electricity bills) = kilowatts × hours

Esempi risolti

Ingresso
230 V, 10 A circuit
Risultato
P = 230 × 10 = 2,300 W = 2.3 kW
10-amp ring main in a UK home
Ingresso
2 Ω resistor, 5 A current
Risultato
P = I²R = 25 × 2 = 50 W
Ingresso
3 kW kettle running for 3 minutes
Risultato
Energy = 3 × (3/60) = 0.15 kWh ≈ 4p at 25p/kWh

Domande frequenti

What is Power Calc?

Electrical power is the rate at which electrical energy is transferred or converted. The three equivalent power formulas (P = VI, P = I²R, P = V²/R) allow power to be calculated from any two of the three fundamental quantities (V, I, R)

How accurate is the Power Calc calculator?

The calculator uses the standard published formula for power calc. Results are accurate to the precision of the inputs you provide. For financial, medical, or legal decisions, always verify with a qualified professional.

What units does the Power Calc calculator use?

This calculator works with inches, kilowatts, watts. You can enter values in the units shown — the calculator handles all conversions internally.

What formula does the Power Calc calculator use?

The core formula is: P = V × I (power = voltage × current). Each step in the calculation is shown so you can verify the result manually.

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