옴의 법칙 공식 (V = IR): 무료 계산기 & 풀이 예제

Use V = IR (the IR 공식) for 전압, 전류, or 저항. mA/kΩ traps, 일ed examples, and a free 옴's law calculator.

사용 방법 옴의 법칙 (Quick 답)

옴's law is V = I R (often written V = IR or v = ir). 전압 equals 전류 times 저항. If you know any two of V, I, and R, solve for the third.

  • V = I × R — find 전압.
  • I = V / R — find 전류 (the “IR 공식” rearranged).
  • R = V / I — find 저항.
  • 변환 mA → A (÷ 1000) and kΩ → Ω (× 1000) before substituting.

    • Need a 확인ed number now? Open the free 옴's law calculator (V = IR) — then come back for unit traps and 일ed examples.

    What Is V = IR (the IR 공식)?

    V is 전압 in volts, I is 전류 in amperes, and R is 저항 in ohms. For an ohmic resistor they stay in proportion: raise V at fixed R and I rises; raise R at fixed V and I falls.

    학생 often search “ir 공식” or “v = ir” meaning the same relationship. Once two values are known, the third is fixed — that is why a rearranging calculator covers most home일 확인s.

    Rearrangements

  • V = I × R.
  • I = V / R.
  • R = V / I.

    • 풀기 any form on the free 옴's law calculator.

    When 옴의 법칙 Applies

    Use it when the problem treats the component as an ohmic resistor — a single R that does not change with 전압 in the range you care about. Metal-film resistors in lab kits are the usual case.

    Do not 힘 a single R onto diodes, LEDs, or other non-linear devices unless the question says to.

    단위 Traps

    Milliamps vs amperes

    변환 나누기 전에: 30 mA = 0.030 A. Using 9 / 30 instead of 9 / 0.030 makes R wrong by 1000×.

    Kilo-ohms vs ohms

    2.2 kΩ = 2200 Ω. Leaving kΩ as 2.2 in V = IR breaks the answer.

    전력 vs 옴's law

    Watts use P = V I (or I²R, V²/R). When the unknown is 전력, use the electric 전력 calculator — not 옴's law alone.

    풀이 예제

    예제 1: I from 12 V and 4 Ω

    I = V / R = 12 / 4.0 = 3.0 A.

    예제 2: R from 9 V and 30 mA

    30 mA = 0.030 A. R = 9 / 0.030 = 300 Ω.

    예제 3: V from 0.025 A and 1.2 kΩ

    R = 1200 Ω. V = I R = (0.025)(1200) = 30 V.

    확인 예제 1–3 on the 옴's law calculator.

    옴의 법칙 vs Dividers and Net일s

    옴's law handles one 저항 relationship. For two resistors sharing a supply, use a 전압 divider. For series/parallel pairs, find equivalent R first, then apply V = IR.

    전압 divider calculator.

    Series–parallel 저항 calculator.

    Electric 전력 (P = VI).

    흔한 실수

  • Leaving 전류 in mA while R is in ohms.
  • Treating kΩ as ohms in V = IR.
  • Writing I = R/V instead of I = V/R.
  • 적용ing a fixed R to a clearly non-ohmic device.

    • 무료 옴의 법칙 계산기

    Use the free 옴's law calculator to solve V = IR for 전압, 전류, or 저항 with 단계별 일ing.

    Electric 전력 calculator.

    전압 divider calculator.

    Master V = IR with clean amperes and ohms — then verify every home일 answer.

    문서

    • 탄성 위치 에너지 공식 (U = ½kx²): 계산기 & 예제
    • 계산 방법 전기 전력 (P = VI, I²R, V²/R)
    • 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)

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