Midrar Academy Learning Lab
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Ohm's Law & Power Calculator

Fill in any 2 of the 4 values — the rest are computed automatically.

Formula Wheel — V · I · R · P
Ohm's Law V Volts V = IR V = P/I V = √(PR) P Watts P = VI P = I²R P=V²/R I Amps I = V/R I = P/V I = √(P/R) R Ohms R = V/I R=V²/P R = P/I²
Voltage (V)
V
Current (I)
I
Resistance (R)
R
Power (P)
P
Fill in any 2 values to calculate the remaining 2.
Practical Examples — click to load
💡 LED Resistor
LED: 2V forward, 20mA. Supply: 5V. Find series resistor needed.
🔦 60W Bulb (220V)
60W light bulb on 220V mains. Find current drawn and filament resistance.
🔌 USB Charger
USB charger: 5V output, 2A current. Find the power delivered.
🫖 Electric Kettle
Kettle rated 2200W on 220V. Find current and resistance of element.
📱 Phone Battery
3.7V battery, 3000mAh. Find energy stored in Wh and P if discharging in 2h.
Unit Conversions Quick Reference
1 mA = 0.001 A 1 kΩ = 1000 Ω 1 MΩ = 1 000 000 Ω 1 mW = 0.001 W 1 kW = 1000 W 1 mV = 0.001 V 1 kV = 1000 V