Ohm's Law Calculator
Calculate Voltage, Current, Resistance, or Power using Ohm's Law.
Ohm's Law Calculator
Enter any two values to calculate the other two.
Ohm's Law Circuit
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Solve for Voltage, Current, Resistance & Power
Our Ohm's Law Calculator allows you to easily solve for any two unknown variables in an electrical circuit by providing the other two known values.
What is an Ohm's Law Calculator?
An Ohm's Law Calculator is a tool that simplifies the fundamental principles of electricity for engineers, hobbyists, and students. It allows you to find an unknown value—voltage (V), current (I), resistance (R), or power (P)—by inputting any two known values. This is essential for circuit design, ensuring components are correctly sized, and for troubleshooting electrical systems.
How It Works: The Ohm's Law Formulas
The calculator is built upon Ohm's Law and the Power Law. The core formulas are:
Voltage (V) = Current (I) × Resistance (R)
Current (I) = Voltage (V) / Resistance (R)
Resistance (R) = Voltage (V) / Current (I)
Power (P) = Voltage (V) × Current (I)
- Enter Two Known Values: Input any two of the four variables: Voltage (in Volts), Current (in Amps), Resistance (in Ohms), or Power (in Watts).
- Leave Others Blank: The fields for the two unknown values should be left empty.
- Calculate: The calculator will use the appropriate Ohm's Law formulas to instantly solve for the two missing values.
Interpreting the Results: Circuit Analysis
The results provide a complete picture of your circuit's basic parameters. For example, if you calculate **Power (P)**, you know how much heat a component will dissipate, which is crucial for selecting components that won't overheat. If you solve for **Current (I)**, you can choose the correct fuse or wire gauge. Solving for **Resistance (R)** helps you select the right resistor for a circuit.
Common Electrical Misconceptions
- Myth 1: Voltage is what kills you. It's actually the current (amperage) flowing through the body that is most dangerous. Voltage is the pressure that pushes the current, but a high voltage with very low current may not be lethal, while a lower voltage with high current can be.
- Myth 2: Electricity takes the path of least resistance. Electricity takes *all* available paths, but the current divides itself inversely proportional to the resistance of those paths. More current will flow through the path of least resistance, but some will flow through all paths.
- Myth 3: All batteries are the same voltage. Batteries come in many different voltages. A standard AA battery is 1.5V, while a car battery is 12V. Using the wrong voltage can damage a device.
Frequently Asked Questions
What is the formula for Ohm's Law?
The formula for Ohm's Law is V = I × R, where V is voltage, I is current, and R is resistance. Our Ohm's Law Calculator allows you to solve for any of these three variables, as well as power (P).
What is Ohm's Law used for?
Ohm's Law is used to calculate the relationship between voltage, current, and resistance in an electrical circuit. It is fundamental for designing, analyzing, and troubleshooting electronic circuits to ensure components operate correctly and safely.
How do you calculate power using Ohm's Law?
Power (P) can be calculated in several ways using Ohm's Law: P = V × I (voltage times current), P = I² × R (current squared times resistance), or P = V² / R (voltage squared divided by resistance).
Does Ohm's Law apply to all components?
No, Ohm's Law primarily applies to 'ohmic' components, where the resistance is constant regardless of the voltage, such as resistors. It does not apply to non-ohmic components like diodes or transistors, where the relationship between voltage and current is not linear.
Practical Application Tips
- Check Component Ratings: When calculating power, ensure the result does not exceed the power rating (in Watts) of your resistor to prevent it from burning out.
- Measure with a Multimeter: For real-world applications, use a multimeter to verify your calculated values.
- Consider the Source: Remember that the voltage source (like a battery or power supply) must be able to supply the calculated current (I).
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