[Encyclios]

Types and forms of energy

Essentially the total energy of a system can be subdivided into potential (stored) energy or kinetic (working) energy, or combinations of the two in various ways. While these two categories are sufficient to describe all forms of energy, it is often convenient to refer to particular combinations of potential and kinetic energy as its form.

Energy tends to pass from one form to another, so the various forms of energy do not remain perpetually as they are, but are transformed into each other: for example, chemical energy is often transformed into heat and sometimes (as in the case of the battery) into electrical energy; nuclear energy and mechanical energy are transformed spontaneously into heat.

The conversion of energy from one form to another can occur spontaneously or in an induced manner, through special machines or systems. With an electric generator, mechanical energy can be transformed into electrical energy, while with an electric motor, electrical energy is transformed into mechanical energy. With an internal combustion engine, of the type used in common cars, the chemical energy of the fuel is used, which is transformed, during combustion (which is a chemical reaction), into thermal energy and then into mechanical energy to drive the wheels of the car. In a common neon tube, electrical energy is transformed into electromagnetic energy, emitted by excited neon atoms in the form of luminous radiation or light. In nature, plants, by means of a green pigment present in the leaves, the chlorophyll, intercept the radiant energy coming from the Sun and transform it into chemical energy (photosynthesis).

In general, for each energy transformation it is possible to calculate the efficiency of the transformation, which measures as a percentage how much of the energy input in a form has been converted into the desired final form. In the case of spontaneous transformations the efficiency is always 100%, while in the case of induced transformations it depends on the type of instrument used and the initial and final forms of energy. Among the various forms of energy, thermal energy has an interesting characteristic: all other forms of energy can spontaneously transform into thermal energy, but the opposite is not true. Because it is related to the motion of atomic-molecular agitation, thermal energy is the most disordered form of energy, or, as they say, the most degraded.

• Chemical energy
• Dark energy
• Electric energy
• Gravitational energy
• Internal energy
• Magnetic energy
• Mechanical energy
• Kinetic energy
• Potential energy
• Elastic energy
• Quantum chromodynamics binding energy
• Radiant energy
• Rest energy
• Soundwave energy
• Thermal energy