Ohm's Law Calculator
Calculate voltage, current, resistance, and power in electrical circuits using Ohm's Law.
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Table of Contents
Ohm's Law Formula
Ohm's Law is a fundamental principle in electrical engineering that describes the relationship between voltage, current, and resistance in an electrical circuit.
Where:
- V = Voltage (in volts)
- I = Current (in amperes)
- R = Resistance (in ohms)
How to Calculate
To calculate using Ohm's Law, follow these steps:
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1Identify which two values you know (voltage, current, or resistance)
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2Use the appropriate formula to find the third value
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3Calculate power using P = V × I
Power Calculations
Power in an electrical circuit can be calculated using any of these equivalent formulas:
P = I² × R
P = V² / R
Where P is power in watts (W)
Practical Examples
Example 1 Basic Circuit
A circuit has a voltage of 12V and a current of 2A. Calculate the resistance and power.
R = V/I = 12V/2A = 6Ω
P = V × I = 12V × 2A = 24W
Example 2 LED Circuit
An LED with a forward voltage of 3.3V and current of 20mA. Calculate the required series resistance for a 5V power supply.
V_resistor = 5V - 3.3V = 1.7V
R = V/I = 1.7V/0.02A = 85Ω
Example 3 Power Supply
A device requires 5W of power at 12V. Calculate the current and resistance.
I = P/V = 5W/12V = 0.417A
R = V/I = 12V/0.417A = 28.8Ω