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YUGUANG's Ohm's Law Calculator helps engineers and students quickly calculate resistance, current, voltage, and power in an electrical circuit. Simply enter any two known values, and the calculator will instantly compute the remaining parameters. This fast and easy-to-use online tool illustrates the fundamental relationship between voltage, current, and resistance, making it essential for circuit design, troubleshooting, and electronics learning.
Enter your parameters below to calculate results.
For certain conductors of electricity, the electric current passing through them is directly proportional to the voltage applied. This relationship relies on the fact that the drift velocity of charges through the material is proportional to the electric field in the conductor.
The resistance is the ratio of voltage to current. If this ratio remains constant over a broad range of voltages, the material is considered "ohmic." If the resistance of a substance is known, the current can be predicted using the fundamental relationship known as Ohm's Law.
An Ohm's Law Calculator is a handy tool for determining the mathematical relationship between voltage, current, and resistance across a conductor. These formulas are fundamental in electrical engineering and electronics. Understanding how to calculate these values, along with power, is essential for analyzing electronic circuits.
Ohm's Law asserts that if all physical parameters (such as temperature) remain constant, the voltage across a conductor is directly proportional to the current flowing through it. Resistance () is the constant of proportionality in this equation, measured in units of ohms ().
Ohm's Law defines how current flows through a resistance when a distinct electric potential (voltage) is applied. This is often compared to water flowing through a pipe:
Higher pressure (voltage) or a wider pipe (lower resistance) results in more water flow (current).
The relationship describes the link between Voltage (), Current (), and Resistance ().
1. Voltage Formula The voltage in volts () is equal to the current in amps () multiplied by the resistance in ohms ():
2. Power Formula The power in watts () is equal to the voltage multiplied by the current :
3. Resistance Formula Resistance can be calculated as the quotient of voltage and current:
4. Current Formula Current is equal to voltage divided by resistance:
Note: Ohm's law strictly applies to ohmic materials (like metals and ceramics) under constant conditions. Non-linear devices like semiconductors and insulators may not follow this linear relationship strictly.
In Alternating Current (AC) circuits, resistance is replaced by Impedance ().
Voltage in AC:
(Where is Impedance in )
Complex Power () in Volt-Amps ():
The Ohm's Law Triangle is a visual tool to help remember the three main formulas. Voltage () is always at the top, with Current () and Resistance () at the bottom.
The "Formula Wheel" combines Ohm's Law with the Power formula () to show the relationships between Power (), Current (), Voltage (), and Resistance (). This creates four quadrants, each offering three formulas to solve for a specific variable.
Tip: Always ensure units are consistent (e.g., convert Milliamps to Amps or Kilohms to Ohms) before calculating.
Scenario 1: You have a 120 Volt () light bulb that draws 0.625 Amps () of current. What is the resistance?
Scenario 2: You know the current () and the filament resistance (). Can you find the voltage? Yes, using the Triangle:
You can determine the values in any circuit in three simple steps:
Definitions:
Ohm's Law is straightforward yet critical for all circuit design. By knowing just two of the three variables, you can easily determine the third. This cornerstone of electrical engineering underpins the inner workings of every circuit, from the simplest flashlight to the most complex motherboard.