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# Ohm's Law

Updated: Aug 27, 2020

Ohm's Law is an equation that lets you calculate the relationship between current, voltage, and resistance in a circuit. Before getting deep into the properties and characteristics let us check out history about this famous law.

## History

Ohm's law as the name implies was discovered by a scientist named Georg Simon Ohm who was able to successfully derive the relationship between current, voltage, and resistance. He completed multiple experiments on the thermocouple, voltaic piles, etc and published work on resistance which was accepted worldwide.

In order to fully capture Ohm's Law, we should be able to understand the terms used in it.

• Current: Current is the rate at which electrons flow from one point to another in a closed electrical circuit. It is usually measured in Amperes. So, one Ampere is defined as a unit coulomb of charge moving ahead of a point in the circuit.

• Voltage: It is simply an electromotive force or potential that is needed for this current to pass through the circuit. It is measured in Volts. So, one Volt is defined as the potential difference between any two points in a closed circuit.

Ohm's Law states that the voltage between two points in a circuit is directly proportional to the product of current and resistance.

Mathematically, E = I x R where E is voltage, I is current and R is resistance

From this equation, it can be deciphered that, if any one of the values is not available, it could be easily calculated by rearranging the equation. Let us understand the concept of Ohm's Law with an example.

Assume that in a given circuit, the current is 1 Ampere and the voltage is 1 Volt. How do we find the value of resistance?

Simple, Resistance will be equal to Voltage/Current. Therefore we get the value of resistance as 1 Ohm.

This also covers the definition of 1 Ohm resistance.

1 Ohm is defined as the resistance of a conductor when a potential difference of 1 volt applied to the ends of a circuit through which 1 Ampere current flows.

## The iconic Ohm's Law Graph

We have seen that the current and voltage are directly proportional and the value of resistance depends on these two entities. So the graph of Ohm's Law will be as follows. After going through these facts, you would have understood that Ohm's Law is an equation that is an inevitable part of electronics and physics and provides a basis for all the circuitry that we do it. Hence each and every person in this field must be aware of it.

### Applications of Ohm's Law in everyday life

Ohm's law is used in many of our everyday applications knowingly or unknowingly. Let us take a look at some of the common ones.

1. Domestic Fans: We all probably have fans at our houses and a respective regulator to control the speed. There is a potentiometer in the system that allows the regulator to shift from one resistance to another and thus control the power of the fan.

2. Laptop and Cellphone chargers: Charges simply use DC power and give out variable resistance based on the working of Ohm's law.

3. Design of Fuse: While connecting a fuse, it has to be designed properly in series and configured according to Ohm's law for safe and protected usage.

4. Electronic appliances: Some common electronic appliances such as kettles and iron contain multiple resistors inside them. Ohm's law plays an instrumental role in determining the amount of heat that should pass through the device and work efficiently.