Demonstrated that electric circuits obey the law of the conservation of energy and that electricity is a form of energy First Law of Thermodynamics.

Clausius demonstrated in 1850 that caloric theory could be reconciled with kinetic theory provided that the conservation of energy was employed rather than the movement of a substance, and stated the First Law of Thermodynamics.

These discoveries came before the first law of thermodynamics, in 1845.

The state function was called the internal energy and it became the first law of thermodynamics.

This is also called the first law of thermodynamics.

This results in the following for the first law of thermodynamics:

The sign of work in the first law of thermodynamics.

The first law of thermodynamics tells us that energy can neither be created nor destroyed.

The first law of thermodynamics was expressed in two ways by Clausius.

The first law of thermodynamics may be stated in several ways:

Beginning with the first law of thermodynamics for an open system, this is expressed as:

From the first law of thermodynamics we find: .

These statements preceded the first law of thermodynamics (1845) and helped in its formulation.

"That's the first law of thermodynamics," I said, wiping my nose.

The above two equations in the first law of thermodynamics imply for a closed system:

The first law of thermodynamics gives for adiabatic contraction.

The first law of thermodynamics says that the increase in internal energy is equal to the heat added minus the work done on the surroundings.

For reversible processes, the first law of thermodynamics requires that:

The first law of thermodynamics tells us that energy may be converted from one form to another without any of it being destroyed.

For a reversible process, the first law of thermodynamics gives the change in the system's internal energy:

For a closed thermodynamic system, the first law of thermodynamics may be stated as:

The first law of thermodynamics is essentially a statement of conservation of energy.

The first law of thermodynamics states that the internal energy of an isolated system is conserved.

The first law of thermodynamics refers to the change of internal energy of the open system.

Next we recall the thermodynamic identity (from the first law of thermodynamics):

To avoid violating the first law of thermodynamics, this extra mass is usually described as having been "borrowed" from a nearby star.

The most common wording of the first law of thermodynamics used by scientists is: