Ohm’s law is the most basic and most important law in electronics. Ohm’s law, in simple terms, states that current passing through a conductor is directly proportional to voltage. Read on to understand further.

What is Ohm’s law?

Let us see how Ohm’s law works.

Imagine,  a pipe is connected to a tap. Turn the tap ON a little bit, the water will comes out slowly from the pipe. Now, open the tap further, you can notice the speed of the water increases. When you open the tap to the fullest you can see the water coming out with maximum speed. When, you insert some pieces of paper or cloth in your pipe or just put your finger at the end, what do you see? The speed of the water changes.

Similar to this is the case of electric current. When, you connect a battery to a wire. The voltage of the battery provides the speed to the current. This speed of current is measured in Amperes.

As we use a blockage to control the speed of water in a pipe, we use resistors, to control the current flowing in a circuit.

If you haven’t read about circuits. Read here

Ohm’s Law states,

The potential difference (voltage) across an ideal conductor is proportional to the current through it.

According to our tap example, it can be restated as,

The speed of water flowing in a pipe depends on how much the tap is open.

 

Voltage, Current, Resistance and Conductance

 

Voltage – It is a type of electric force that makes electricity run through a wire. It is measured in volts. It is represented by a symbol V.

Current- Voltage does not go anywhere, what flows in a circuit is current. When electrons move forward(in any one direction) in a wire, we say that the current is flowing in it. It is measured in Amperes(Symbol – A)

Resistance – It fights with the current and stops it from moving forward. It is measured in Ohms(Symbol – Ω)

There is another interesting term which is the opposite of resistance, it is called conductance. Like the resistance measures the blockage, the conductance is more positive term and tells us, with how much ease the current can flow.

Conductor is a material through which current can flow easily(like a wire)

We can say that current and conductance are friends, the more the conductance, more easily current can flow.

Current and resistance are enemies, since resistance  restricts the flow of current.

 

Mathematically, Ohm’s Law is

V = I * R

Here V stands for voltage, I for current and R for resistance

 

This law or formula can be used to determine the voltage, when you know the current and resistance flowing in a circuit. The voltage is equal to current multiplied by the resistance.

The above equation can also be written as,

Here, current is equal to voltage divided by resistance.

It can also be written as,

Here, resistance is equal to voltage divided by current.

You can use the triangle given below to remember all the three formulas

Now, relating the formulas with this triangle is pretty easy. We can see that V is equal to I x R, I is equal to V/R and R is equal to V/I.

 

Before ending, some facts…

1. The concept behind Ohm’s law was first explained by German Physicist Georg Ohm who the law is also named after.
2. The tool for measuring volts in an electric circuit is called a voltmeter. An ohmmeter is used for measuring resistance. A multi- meter can measure several functions including voltage, current, resistance, and temperature.