Ohm's Law states V = IR: voltage equals current times resistance. It also implies I = V/R and R = V/I.

Does Ohm's Law apply to all components?

No â€” Ohm's Law applies only to ohmic (linear) components like resistors. It does not apply to diodes, transistors, or other non-linear devices.

Ohm's Law Calculator â€” V=IR, I=V/R, R=V/I

⚡ Ohm's Law Calculator

Enter any TWO values and leave the third blank â€” the calculator will find it.

Voltage (V) volts

Current (I) amps

Resistance (R) ohms

Enter any two values above

Formulas used

Voltage = Current Ã— Resistance â†’ V = I Ã— R

Current = Voltage Ã· Resistance â†’ I = V / R

Resistance = Voltage Ã· Current â†’ R = V / I

Power = Voltage Ã— Current â†’ P = V Ã— I = IÂ²R = VÂ²/R

Ohm's Law Explained

Ohm's Law states that the current through a conductor is directly proportional to the voltage and inversely proportional to the resistance: V = IR.

It was discovered empirically by Georg Simon Ohm in 1827 and is the foundational law for analysing DC electrical circuits. It applies to ohmic materials (resistors) but NOT to non-linear devices like diodes or transistors.

Power Triangle

Power (P) measured in watts can be found using any combination of V, I, R:

P = V Ã— I
P = IÂ² Ã— R
P = VÂ² / R

Worked Example

A 9 V battery connects to a 270 Î© resistor. Find current and power.

I = V/R = 9 / 270 = 0.0333 A = 33.3 mA

P = VI = 9 Ã— 0.0333 = 0.3 W

Check: P = VÂ²/R = 81/270 = 0.3 W âœ“

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📚 Recommended Reading

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The Art of Electronics

Horowitz & Hill

Intermediate

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Introductory Circuit Analysis

Boylestad

Undergraduate

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