🔧 Engineering Decision Tool D3

Basic

Interactive calculator

Basic electrical calculations for voltage, current, resistance, and power using Ohm's Law and basic power equations.

Calculate V, I, or R from two known values.

📥 Input Parameters

📐 Calculation Steps

Identify knowns

Ohm's Law

You need two of three: V, I, R.

Solve unknown

V=IR, I=V/R, R=V/I

Apply Ohm's Law.

🧮 Formula

Ohm's Law & Power

V = I*R; P = V*I = I^2*R = V^2/R

Fundamental relationships in DC circuits.

Symbol	Variable	Unit
V	Voltage	V
I	Current	A
R	Resistance	ohm
P	Power	W

📋 Worked Example: 12V LED Circuit

Result:

🔍 Result Interpretation

✅ Standard resistor

✅ Power dissipation

💡 Engineering Recommendations

🔧

Using E12 resistor values

Calculate exact R then pick nearest standard E12/E24 value.

E12: 1.0, 1.2, 1.5, 1.8, 2.2, 2.7, 3.3, 3.9, 4.7, 5.6, 6.8, 8.2 x decade.

⚡ Quick Facts

V=IR - memorize it

Ohm's Law

P=VI = I^2R = V^2/R

Power

🔬 Engineering Insight

"The most common mistake in basic electrical calculations is mixing units. Always convert to base units before calculating: kohm -> ohm, mA -> A, kV -> V."

📜 Standards & References

IEC 60063 — IEC

Preferred number series for resistors.

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❓ Frequently Asked Questions

🔧 Related Calculators

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Ohm's Law Calculator

📖 Related Knowledge

→ Ohm's Law Fundamentals

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