Ohm's Law Definition, Formula, Example - V = I * R (2024)

Ohm’s Law Definition, Formula, Example Explained in Detail.

Ohm’s law describes the relationship between Voltage, Resistance and Current where Voltage (V) is trying to force charge to flow, Resistance (R) is resisting that flow, and the actual resulting Current (I).

Ohm’s Law Definition

1. Ohm’s Law states that electric current is proportional to voltage and inversely proportional to resistance.
2. Mathematically, the law states that V = IR, where V is the voltage difference, I is the current in amperes, and R is the resistance in ohms.

Who Invented Ohm’s Law?

Ohm’s Law is Named after the Great German Physicist and Mathematician – Georg Simon Ohm. He was born on March 16, 1789 and died on July 6, 1854.

Georg Simon Ohm did a research on the Battery Invented by the Italian scientist Alessandro Volta.

He concluded his research with a Formula which states that the current flow through a conductor is directly proportional to the potential difference (voltage) and inversely proportional to the resistance. This relationship is known as Ohm’s law.

Ohm’s Law Formula

The Ohm’s law formula helps to calculate voltage, current and resistance.

I = V / R; where

• I = Electrical Current Flowing through the Resistor
• V = Voltage Drop of the Resistor
• R = R is the resistance of the resistor, measured in Ohms (Ω)

Understanding Ohm’s Law

As per the law, we can state that:

1. Large voltage and low resistances produces large current.
2. Large resistance limit current to low values.

Question: Almost every electric circuit is more complicated than just a basic circuit with a battery and a resistor. So which voltage does the formula refer to?

Answer: Well, it refers to the voltage across the resistor, the voltage between the two terminal wires.

Looked at another way, that voltage is actually produced by the resistor.
The resistor is restricting the flow of charge, slowing it down, and this creates a traffic jam on one side, forming an excess of charge with respect to the other side.

Any such charge difference or separation results in a voltage between the two points.

Ohm’s law tells us how to calculate that voltage if we know the resistor value and the current flow. This voltage drop is analogous to the drop in water pressure through a small pipe or small nozzle.

Examples

Example-1: Find the current of an electrical circuit that has resistance of 100 Ohms and voltage supply of 10 Volts.

Solution:

• V = 10 V
• R = 100 Ω
• I = V / R = 10V / 100Ω = 0.1A = 100mA

Example-2: Find the voltage applied across 100 kΩ resistors when 5 mA current flows through it

Solution: V = 100 kΩ * 5 mA = 500 V

Example-3: Find the value of a Resistor which drops 100 V when 50 mA current is flowing through it.

Solution: R = 100 V / 50mA = 200 Ω

Video: Understand What is Ohms Law

FAQs: What is Ohm’s Law?

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