What is the Joule effect and why it has become crucial for our lives

What is the Joule effect and why it has become something momentous for our lives

Heat and electric currents always go together hand in hand. For better and for worse.

Surely more than once heard the word, and not referring to July month calendar-or, on the contrary, the word Joule (July word in English). This comes, in the field of science, the English physicist James Prescott Joule (1818-1889), who made several studies related to the movements of subatomic particles , electrical currents and power generation .

This physical was the father of “Joule effect” or “law of Joule” , one of the pillars that allow the development and operation of many of the products we around today. But what the Joule effect? What is the significance of the studies conducted by the British physicist?

Understanding energy and heat

To understand the Joule effect, we briefly clarify the concept of heat. Heat it is known as the release of energy by a system as the cause of motion, on a microscopic scale, the particles that compose it.


Electrons move in a totally random, impacting interacting with other particles and, therefore, creating movement and heat release

For example. if you heat a pot of water, which actually occurs is an increase in energy of the system, which, at the molecular level, translates to greater movement of the particles that make up the system . This energy “absorbed”, later, was again clear to the outside as heat, provided the environment that surrounds this system has a lower energy levels (in this case, so, as the air surrounding the pot usually at a lower temperature).

Why this energy is released rather than conserve it? All systems tend by nature to seek a standstill or rest or calm -clearly calm the situation in which the movement of the particles is possibly the least. Therefore, when this state of relative calm is disturbed, the systems exchange energy with those around them to try to close as possible to that state. In the case of the pot, heat to the outside to try to “cool down” and reduce their energy level is emitted. That exchange of energy is what we call heat.

What is the Joule effect and why it happens

Joule Effect

Nikolay Neveshkin / Shutterstock.com

The Joule, as the crow flies, is the release of heat caused by the movement of electrons also known as current electrically for material. This effect is reflected in the formula Q = P xt , where “Q” is energy or heat release (also represented by the letter E and measured in Joules or Calories), “P” power consumption ( measured in watts) and “t” elapsed time (in seconds).

To understand the Joule effect, must understand the origin of the electrical currents . To do this, imagine a simple circuit with a 6-volt battery (with positive and negative) and a resistance of about 3 ohms.

  1. When connecting the battery to the circuit, the electrons stored in the stack will begin to go through the circuit from the positive terminal to the negative , through the wires and the resistor connected to it.

  2. These electrons move because of a difference of potential which, in this case 6 volt-is. To understand this concept, imagine a ladder. The positive pole is the top of the ladder. The negative pole, the lower zone. From the top, we roll balls. These will inevitably begin to fall down by gravity. With electrons something similar happens -in fact many gravitational laws also used to perform Power Generators- measurements. This movement of electrons (greater potential) positive terminal to the negative (lower potential) is what we call power.

  3. When those electrons move, these impact with other atoms and subatomic particles (which comprise cables, resistors, etc.) and, therefore, cause these to move in varying degrees. By increasing its movement energy increases and, therefore, the heat release to the outside. This -only release would inevitably avoidable if drivers materials were 100% perfect, something that is impossible to achieve-energy as heat is known as the Joule effect.


The heaters are a clear example of application of Joule

The Joule effect and the amount of heat depends on several variables follows.

  • The current. or the number of electrons passing per unit time. To understand this concept, imagine a water pipe. The larger diameter water pipe has, more will flow through it in a unit time. The current intensity is similar. The lower the resistance and the greater the potential difference, the greater will be the number of electrons moving in a unit of time.

  • Resistance. It is the opposition that presents an element to the passage of electrons through it. Normally we understand as a particular resistance element (which may be a light bulb or any other), but resistance is also present on the wires, for example. And everything material through which electrical current passes, has opposed the passage of electrons. If not present, the highest return of all systems and heat generated would be negligible be obtained. So we can better understand this concept, the resistance could be understood as the number of obstacles that would have to negotiate an athlete in a race 200 meters hurdles. The higher the resistance, the greater the number of obstacles that arise in the way of the electron.

  • The potential difference or voltage. Turning the analogy, the potential difference could understand as the height difference exists between the top of a ladder and the bottom. In this example, gravity pulls the bodies of the upper zone. In the case of electricity, atoms are the ones that attract electrons from positive to negative, causing the movement.

  • Time. The the longer the time, the amount of heat generated increases. Therefore also relevant.

  • Power. Normally, the influence of the resistance, the intensity and the potential difference of a circuit meets in a magnitude called power (which is what appears in the formula above).

The Joule, something desired and despised


A priori, the Joule effect may seem totally insignificant, since prevents obtaining the maximum amount of energy of an electric current that feeds a system. For example, the processor is something I always try to avoid, because it is take advantage of the greater amount of electrical energy to increase the performance of your computer, tablet or smartphone to which it is connected.

The Joule effect is praise indeed and at the same time, despised But Joule also is something very desirable and essential to many current products. products like stoves, heaters, water heaters, dryers or glass ceramics. And this effect can convert electrical energy into heat, which has been exploited by engineers during the last century to the creation of a host of products.

In the case of dryers, for example we find a series of resistors that are heated by the passage of electric current, thus heating the air expelled outside . The game is to try to obtain greater energy efficiency (with the least amount of electricity possible, heat the air at the same temperature).

So the Joule effect is, like everything in life, something very relative . Depending on the area and the situation in which we find ourselves, we are interested in their appearance or not. But that’s something you have to deal while electricity is one of the foundations of our society


What is the Joule effect and why it has become crucial for our lives
Source: english  
May 24, 2015

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