Voltage Calculator
Calculate voltage using Ohm's Law: V = I × R. Enter current and resistance to find voltage.
Enter Values
Fill in the fields and press Calculate to see instant results.
What is the Voltage Calculator?
The Voltage Calculator uses Ohm's Law to calculate the voltage across a component when you know the current and resistance. Simply enter the current (in amperes) and resistance (in ohms), and the calculator instantly computes the voltage.
Formula
Ohm's Law states:
Where:
- V = Voltage (measured in volts)
- I = Current (measured in amperes)
- R = Resistance (measured in ohms)
How to Use
- Enter the Current (I) in amperes (A)
- Enter the Resistance (R) in ohms (Ω)
- Click Calculate
- The calculator displays the Voltage (V) and Power (W)
Worked Example
Given:
- Current (I) = 2 A
- Resistance (R) = 6 Ω
Calculation:
V = I × R = 2 A × 6 Ω = 12 V
Results:
- Voltage = 12 V
- Power = 24 W (calculated as P = V × I = 12 × 2)
Real-World Applications
- LED Circuits: Determine the voltage drop across an LED given its current draw and resistance
- Battery and Load: Calculate the output voltage required for a specific load resistance and current
- Power Supply Design: Find the required voltage for electrical equipment
- Troubleshooting: Verify expected voltage in circuits during diagnostics
Common Tips
- Ensure current is in amperes (A) and resistance is in ohms (Ω) for correct results
- For very small currents, use milliamps (mA) = Current in mA ÷ 1000
- Power is automatically calculated using P = V × I
- This calculator assumes DC (direct current) or AC RMS values
Key Definitions
- Volt (V): The SI unit of electrical potential difference, representing energy per unit charge
- Ampere (A): The SI unit of electric current, measuring the flow of electric charge per second
- Ohm (Ω): The SI unit of electrical resistance, measuring opposition to current flow
- Ohm's Law: Fundamental principle relating voltage, current, and resistance (V = I × R)
- RMS (Root Mean Square): The effective value of AC voltage, equivalent to the DC voltage that would deliver the same power
- DC Voltage: Direct current voltage flowing in one direction, typically from batteries or power supplies
Frequently Asked Questions
What is voltage?
Voltage is the electrical potential difference between two points in a circuit. It's the "push" that drives current through a conductor, measured in volts (V).
How do I calculate voltage using Ohm's Law?
Use the formula V = I × R, where V is voltage in volts, I is current in amperes, and R is resistance in ohms. Multiply the current by the resistance to get the voltage.
What's the difference between DC and AC voltage?
DC (direct current) voltage flows in one direction constantly, like from a battery. AC (alternating current) voltage reverses direction periodically, typically 50-60 times per second in power grids.
Why is knowing voltage drop important?
Voltage drop across components (like resistors) helps verify circuit behavior, troubleshoot problems, and ensure components operate within their safe ranges.
Can voltage be negative?
In DC circuits, voltage polarity matters—negative voltage indicates reversed polarity. In AC circuits, voltage alternates between positive and negative values constantly.
What does RMS voltage mean?
RMS (Root Mean Square) is the effective value of AC voltage. Household AC voltage of 120V or 230V is measured as RMS, which is equivalent to the DC voltage that would deliver the same power.
What's the relationship between voltage and power?
Power increases with voltage at the same current: P = V × I. Higher voltage devices can deliver more power or operate more efficiently than lower voltage devices.