The internal energy of a system is defined as the sum of all microscopic energy forms. These include sensible, latent, chemical, and nuclear energy. Sensible energy is related to the kinetic energies of molecules, whereas latent energy is associated with the phase of the system.

A system in equilibrium will never experience a Total change in energy if there is a local or microscopic change in energy in some ‘sub-portion’ of the system. This would require that the microscopic energy in some other sub-part decrease by a commensurate amount.

Internal energy is the sum of all the microscopic forms of energy of a system. Unlike potential energy and kinetic energy, which relate to the energy of a system with respect to external references, internal energy relates to the energy within the system itself.

In the kinetic theory, heat is explained in terms of the microscopic motions and interactions of constituent particles, such as electrons, atoms, and molecules. The immediate meaning of the kinetic energy of the constituent particles is not as heat. It is as a component of internal energy.

Heat may be defined as energy in transit from a high temperature object to a lower temperature object. An object does not possess “heat”; the appropriate term for the microscopic energy in an object is internal energy.

At macroscopic level there is no difference between work and heat and they are both defined as modes which transfer energy (thermal or mechanical) from one object to another.

Macroscopic Vs Microscopic Two points of view may be adopted: macroscopic or microscopic, Microscopic approach considers the behaviour of every molecule by using statistical methods. In Macroscopic approach we are concerned with the gross or average effects of many molecules’ infractions.

The macroscopic scale is the length scale on which objects or phenomena are large enough to be visible with the naked eye, without magnifying optical instruments.

Light microscopes let us look at objects as long as a millimetre (10-3 m) and as small as 0.2 micrometres (0.2 thousands of a millimetre or 2 x 10-7 m), whereas the most powerful electron microscopes allow us to see objects as small as an atom (about one ten-millionth of a millimetre or 1 angstrom or 10-10 m).

The microscopic scale (from Greek: μικρός, mikrós, “small” and σκοπέω, skopéō “look”) is the scale of objects and events smaller than those that can easily be seen by the naked eye, requiring a lens or microscope to see them clearly.

Plössl eyepieces are good all-around performers, producing sharp images at the center of the field, but they have only four lens elements. Better edge correction with a short-focus telescope is one of the things you pay extra money for, and sophisticated eyepiece designs have as many as eight elements.

For visual use, Barlow lenses from 1.5X to 3X are common. Generally, Barlow lenses of greater than 3X are considered applicable to astrophotography though there is nothing to prevent you from using one with your eyepiece. Barlow lenses come in a variety of designs.