Voltage Calculator | Ohm's Law: Voltage, Current, Resistance, Power

📖 How to Use This Voltage Calculator

Select what to calculate - Choose Voltage (V), Current (I), Resistance (R), or Power (P).

Enter known values - Input the two known quantities (e.g., Current & Resistance for Voltage).

Click "Calculate" - Get the result with proper units (Volts, Amperes, Ohms, or Watts).

⚡ Understanding Ohm's Law

Ohm's Law is a fundamental principle in electrical engineering that describes the relationship between voltage (V), current (I), and resistance (R). The formula V = I × R states that voltage equals current multiplied by resistance.

Power (P) in an electrical circuit is calculated as P = V × I (voltage times current). From these basic equations, you can derive all other relationships.

📊 Ohm's Law Formulas

Voltage: V = I × R
Current: I = V / R
Resistance: R = V / I
Power: P = V × I = I² × R = V² / R

💡 Practical Applications

Circuit Design: Determine appropriate resistor values for LED circuits
Battery Calculations: Calculate current draw and battery life
Home Electronics: Understand appliance power ratings (watts = volts × amps)
Safety: Calculate proper wire gauge for given current
Solar Systems: Design solar panel arrays and calculate voltage drops

🔋 Common Electrical Units

Voltage (V): Electrical potential difference - measured in Volts (V)
Current (I): Flow of electric charge - measured in Amperes (A)
Resistance (R): Opposition to current flow - measured in Ohms (Ω)
Power (P): Rate of energy transfer - measured in Watts (W)

❓ Frequently Asked Questions (FAQ)

What is Ohm's Law and why is it important?

Ohm's Law (V = IR) is the fundamental relationship between voltage, current, and resistance in electrical circuits. It's essential for designing and troubleshooting all electronic devices.

How do I calculate power from voltage and current?

Power (Watts) = Voltage (Volts) × Current (Amperes). For example, a device running at 12V drawing 2A uses 24 watts of power.

What is the relationship between resistance and current?

For a fixed voltage, higher resistance means lower current (I = V/R). This is why resistors are used to limit current in circuits.

What units should I use?

Use standard SI units: Volts (V) for voltage, Amperes (A) for current, Ohms (Ω) for resistance, and Watts (W) for power. The calculator accepts decimals for precise calculations.

Can I use this calculator for AC circuits?

Ohm's Law applies to DC circuits and AC circuits with resistive loads. For AC with reactive components (capacitors, inductors), impedance must be considered.

What is a safe voltage for humans?

Low voltage (below 50V) is generally considered safe for dry skin contact. Higher voltages (120V/240V household) can be dangerous and potentially lethal. Always follow electrical safety guidelines.