What is Ohm's Law?
1 Answer
Ohm's Law Explained: Formula, Examples, and Key Concepts
Ohm's Law is one of the most fundamental and essential principles in the world of electronics and physics. It provides a simple but powerful description of the relationship between voltage, current, and resistance in an electrical circuit. Whether you're a student, a hobbyist, or an engineering professional, understanding Ohm's Law is crucial.
This guide breaks down everything you need to know, from the core formula to practical examples.
What is Ohm's Law?
Ohm's Law, discovered by German physicist Georg Simon Ohm in 1827, defines the relationship between three key electrical quantities:
- Voltage (V)
- Current (I)
- Resistance (R)
The law states that the current flowing through a conductor is directly proportional to the voltage across it, assuming all physical conditions and temperature remain constant.
As illustrated in a basic circuit, a voltage source (like a battery) provides the "push" (Voltage) that causes electrical charge to flow (Current) through a component that resists this flow (Resistance).
The Ohm's Law Formula
The primary formula for Ohm's Law is:
V = I × R
Where:
V represents Voltage, measured in Volts (V).
I represents Current, measured in Amperes (A).
* R represents Resistance, measured in Ohms (Ω).
How to Calculate Voltage, Current, and Resistance
By rearranging the main formula, you can solve for any of the three variables. These variations are essential for circuit analysis.
- To Calculate Voltage (V):
V = I × R - To Calculate Current (I):
I = V / R - To Calculate Resistance (R):
R = V / I
Ohm's Law Example Calculation
Let's apply the formula to a real-world problem.
- Given: A circuit has a Voltage (V) of 9 volts and a Resistance (R) of 3 ohms.
- Find: The Current (I) flowing through the circuit.
Solution:
We use the formula to find the current: I = V / R
I = 9 V / 3 Ω
I = 3 A
Therefore, the current flowing through the circuit is 3 Amperes.
Key Relationships in Ohm's Law
Ohm's Law also helps us understand the direct and inverse relationships between the variables:
- Voltage and Current: If resistance is kept constant, increasing the voltage will cause the current to increase. (↑ Voltage → ↑ Current)
- Resistance and Current: If voltage is kept constant, increasing the resistance will cause the current to decrease. (↑ Resistance → ↓ Current)
It's important to note that this describes a linear relation that is only accurate for materials (ohmic conductors) at a constant temperature.
Quick Reference Table
This table summarizes all the components of Ohm's Law for easy reference.
| Quantity | Symbol | Unit | Formula |
|------------|:------:|-------------|-------------|
| Voltage | V | Volts (V) | V = I × R |
| Current | I | Amperes (A) | I = V ÷ R |
| Resistance | R | Ohms (Ω) | R = V ÷ I |
By mastering these simple formulas and concepts, you can unlock a deeper understanding of how electrical circuits function.