# The role of the first and second Ohm’s law in the electronic cigarette Modified on: 06/12/2022

## Ohm’s laws and e-cigarettes: what is the correlation? Here’s what you should know.

Suppose you are a vaping enthusiast and would like to switch from classic electronic cigarette kits to mechanical and rebuildable e-cigarettes made piece by yourself. In that case, you must know the first and second Ohm’s laws.

Knowing the principles of electricity on which the functioning of an electronic cigarette depends is significant to vape safely and to use and choose the various components in the right way.

Here is what you should know.

### What are Ohm’s laws? Here are the first and second.

Suppose you are an e-cigarette lover and would like to have the best experience with your favourite vape liquids. In that case, you must know Ohm’s laws, the physical principles on which e-cigarette operation is based.

Ohm’s laws are named after their inventor, Georg Ohm, a German physicist who, in an 1827 treatise — going against the beliefs of the time — came up with two innovative formulas.

Ohm’s theories were created to demonstrate the relationship between the voltage applied to the ends of a resistive wire carrying an electric current, the intensity of the current and the wire’s electrical resistance.

#### Ohm’s first law

Ohm’s first law says that in a conducting wire, the intensity of the current (I) is directly proportional to the potential difference (V), or in other words, it is directly proportional to the voltage.

At the same time, the intensity of the current is inversely proportional to the resistance (R).

The formula for Ohm’s first law is, in fact:

I = V / R

To explain the concept in simpler words, we can say that:

• the current increases if you increase the battery voltage or decrease the circuit resistance;
• the current decreases if you lower the battery voltage or increase the circuit resistance.

#### Ohm’s second law

Ohm’s second law states that in a conducting wire, its resistance (R) is directly proportional to its length (l) and inversely proportional to its cross-sectional area (S).

The resistance, however, also changes depending on the material of the resistive wire, which is denoted by the Greek letter ‘ro’ (ρ).

The formula for Ohm’s second law is, in fact:

R = ρ * l / S

### Relationship between e-cigarettes and Ohm’s law

Are you wondering what these physical laws have to do with your e-cigarette and your beloved creamy and fruity liquids?

Well, they do!

Ohm’s laws regulate the proper functioning of the electrical components of vaping devices, so if you’re planning to use a mechanical one, you should be familiar with them.

In particular, using the formulas of Ohm’s laws, you can calculate:

• the amount of current flowing through the resistor (in amperes);
• the Ohm value of the coil resistance;
• the voltage applied to the coil based on the energy delivered by the battery (in Volts).

Thanks to all these values, it will also be possible to determine the power of the electronic cigarette (in Watt) and, using the inverse formulae, to obtain many other valuable data.

Electronic cigarettes are, in fact, devices with a battery with a specific voltage and two poles (+ and -), which is connected to the resistance (or coil) to heat it, employing your current supply. It is the heating of the coil that enables electronic cigarette liquids to be vaporized.

Knowing the first and second Ohm’s law allows you to find the correct resistance for your e-cigarette battery and avoid unpleasant accidents (such as explosions), which could be very dangerous.

### Mechanical e-cigarette and Ohm’s law: application

After explaining them theoretically, let’s find out how Ohm’s laws are used in practice.

Before continuing, you should know that any e-cigarette battery can only deliver continuous discharge current up to a certain level.

Above this level, there is a danger of overheating the battery, which can cause a short circuit or leakage of the gases contained in the battery.

That’s why it’s essential to keep an eye on the intensity of the current, which we’ll refer to as ‘I’ in the formula.

Let’s get started.

• Calculating the current flowing through the resistor
If, for example, you have a 0.5 Ohm coil and a 4.2-volt battery, then according to Ohm’s first law (I = V / R), you should divide 4.2 by 0.5, and you will find that you are dealing with an intensity of 8.4 amps.
If this value does not exceed the maximum current that the battery can deliver, then you are in the clear. Otherwise, to lower the current intensity, you should increase the Ohm value of the resistor.
• Calculating the minimum resistance value based on the continuous discharge current of the battery
Suppose you have a device with a 4.2-volt battery and a maximum continuous discharge current limit of 15 amps, using the formula R = V / I and choosing to use at most 80-90% of the current (equivalent to about 13 amps). In that case, the calculation is as follows: R = 4.2 / 13 = 0.32 Ohm.
Based on this calculation, we have found the resistance figure, within which it would be better not to go down.

Finally, thanks to this data, you can calculate the voltage load that passes through the resistor with the formula V = I * R and the power or wattage of your e-cigarette with the formula P = V * I.

### To conclude

Now you know the very useful Ohm’s law, and you can use it to use your next mechanical e-cigarette in the best possible way.