계산 방법 전기 전력 (P = VI, I²R, V²/R)

계산 electric 전력 with P = VI, P = I²R, and P = V²/R. Pick the right form, fix mA/kΩ traps, and use a free electric 전력 calculator.

What 전기 전력 Asks

Electric 전력 is how fast electrical 에너지 is transferred in a circuit. A bulb rated 60 W converts 60 joules of electrical 에너지 into light and heat every second.

The basic 공식 is P = V I — 전압 times 전류. When the load obeys 옴’s law, you can also write P = I²R or P = V²/R. All three give 전력 in watts when V is in volts, I in amperes, and R in ohms.

If you already have two of V, I, R, or P, open the free electric 전력 calculator first, then return here for which form to pick and unit traps.

The 공식s

  • P = V I — 전력 from 전압 and 전류.
  • P = I² R — 전력 from 전류 and 저항.
  • P = V² / R — 전력 from 전압 and 저항.
  • I = P / V — rearrange when 전력 and 전압 are given.

    • These resistor forms come from substituting 옴’s law V = IR into P = VI. Use the form that matches the two values you already know — do not mix forms carelessly.

    전기 전력 vs Mechanical 전력

    Both are measured in watts, but the inputs differ. Mechanical 전력 is often P = W/t or P = Fv (일 or 힘 and 속력).

    Electric 전력 uses circuit quantities. If a lifting problem asks for watts, use mechanical 전력. If a resistor or bulb asks for watts, use P = VI. 참고 the mechanical 전력 guide and the

    일 vs 전력 exam traps.

    Link to 옴’s Law

    Need V, I, or R first? Use the 옴's law calculator with V = IR, then plug into the matching 전력 form.

    For two-resistor net일s, find equivalent 저항 with the series-parallel calculator before computing 전력 for the combined load.

    단위

  • V → volts (V).
  • I → amperes (A). 변환 mA → A (÷ 1000).
  • R → ohms (Ω). 변환 kΩ → Ω (× 1000).
  • P → watts (W). 1 W = 1 J/s.
  • Leaving mA or kΩ unconverted makes P wrong by large factors.

    • 풀이 예제

    예제 1: P = VI

    V = 12 V, I = 2.0 A. P = (12)(2.0) = 24 W.

    예제 2: P = I²R

    I = 0.50 A through R = 40 Ω. P = (0.50)²(40) = 0.25 × 40 = 10 W.

    예제 3: P = V²/R

    V = 120 V across R = 240 Ω. P = (120)² / 240 = 14400 / 240 = 60 W.

    예제 4: find 전류 from 전력

    P = 60 W, V = 120 V. I = P/V = 60/120 = 0.50 A.

    흔한 실수

  • Mixing milliamps with ohms without converting to amperes.
  • Using P = I²R when you only know V and R (use P = V²/R instead).
  • Confusing mechanical P = W/t with electric P = VI.
  • Forgetting that 전력 in a resistor becomes heat (I²R losses).

    • 확인 It on the 계산기

    Electric 전력 calculator — P = VI, I²R, V²/R.

    옴's law calculator.

    Series-parallel 저항 calculator.

    Mechanical 전력 calculator — P = W/t.

    학습 P = VI and confirm every home일 number on the calculator.

    문서

    • 탄성 위치 에너지 공식 (U = ½kx²): 계산기 & 예제
    • 계산 방법 파동 속도 (v = fλ): 주파수 × 파장
    • 계산 방법 무게 (W = mg): 질량 vs 힘
    • 계산 방법 밀도 (ρ = m/V): 질량 ÷ Volume
    • 계산 방법 가속도 (a = (v − u)/t)
    • 계산 방법 힘 (F = ma): Newton’s Second Law

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