James Prescott Joule

Physics England 1818 – 1889 100 quotes

English physicist who experimentally determined the mechanical equivalent of heat, foundational to the first law of thermodynamics.

Quotes by James Prescott Joule

My object has been to discover the law of the heating effect of the electric current.

On the Production of Heat by Voltaic Electricity 1840

The grand agents of nature are, by the Creator's fiat, indestructible; and, wherever mechanical force is expended, an exact equivalent of heat is always obtained.

On the Calorific Effects of Magneto-Electricity, and on the Mechanical Value of Heat 1843

The force of gravity, when it acts through a given space, produces a given quantity of heat.

On the Calorific Effects of Magneto-Electricity, and on the Mechanical Value of Heat 1843

The amount of heat produced by friction is always proportional to the force expended.

On the Mechanical Equivalent of Heat 1845

The quantity of heat produced by the friction of bodies, whether solid or liquid, is always proportional to the force expended.

On the Mechanical Equivalent of Heat 1847

I am satisfied that the heat occasioned by the friction of fluids is proportional to the force expended.

On the Mechanical Equivalent of Heat 1847

The production of heat by the friction of fluids is a phenomenon of the same nature as the production of heat by the friction of solids.

On the Mechanical Equivalent of Heat 1847

The mechanical equivalent of heat is a constant quantity.

On the Mechanical Equivalent of Heat 1847

The heat produced by the friction of water is proportional to the force expended.

On the Mechanical Equivalent of Heat 1849

The mechanical equivalent of heat, as determined by the friction of water, is 772 foot-pounds.

On the Mechanical Equivalent of Heat 1849

It is difficult to conceive of a more beautiful or more universal law than that which we have been considering.

On the Mechanical Equivalent of Heat 1849

The principle of the conservation of energy is the grandest generalization of modern science.

Letter to William Thomson 1850

The heat produced by the friction of solids is proportional to the force expended.

On the Mechanical Equivalent of Heat 1850

The mechanical equivalent of heat is a constant quantity, whatever may be the nature of the bodies by the friction of which the heat is produced.

On the Mechanical Equivalent of Heat 1850

The heat produced by the compression of gases is proportional to the force expended.

On the Mechanical Equivalent of Heat 1850

The heat produced by the expansion of gases is proportional to the force expended.

On the Mechanical Equivalent of Heat 1850

The mechanical equivalent of heat is the same for all kinds of work.

On the Mechanical Equivalent of Heat 1850

The mechanical equivalent of heat is a fundamental constant of nature.

On the Mechanical Equivalent of Heat 1850

The heat produced by the electric current is proportional to the square of the current and to the resistance of the conductor.

On the Heat Evolved by Metallic Conductors of Electricity 1841

The heat produced by the electric current is independent of the size of the conductor.

On the Heat Evolved by Metallic Conductors of Electricity 1841