Joule’s first law

In the context of resistive circuits and in light of conservation of energy and electrical potential. Joule s first law and Ohm s law are equivalent and derivable from each other, although they were discovered... 

Joule s first law, also known as the Joule effect, is a physical law expressing the relationship between the heat generated by the current flowing through a conductor. It is expressed as ... 

The Joule effect in electrodynamics, also known as Joule s first law, refers to the production of heat by an electrical conductor due to the circulation of charges. Joule studied the phenomenon in the 1840s and expressed his first law as the relationship between the current and the heat production rate ... 

Joule s first law is easily demonstrated in using the general definition of the power entering a dipole ... 

This event marked the turning point in Joule s career. From 1847 on, when Joule spoke, scientists listened. His research results were one of the two major contributions to the establishment of the first law of thermodynamics, the other being that of the... 

Lord Kelvin s close associate, the expert experimentalist J. P. Joule, set about to test the former s theoretical relationship and in 1859 published an extensive paper on the thermoelastic properties of various solids—metals, woods of different kinds, and, most prominent of all, natural rubber. In the half century between Gough and Joule not only was a suitable theoretical formula made available through establishment of the second law of thermodynamics, but as a result of the discovery of vulcanization (Goodyear, 1839) Joule had at his disposal a more perfectly elastic substance, vulcanized rubber, and most of his experiments were carried out on samples which had been vulcanized. He confirmed Gough s first two observations but contested the third. On stretching vulcanized rubber to twice its initial length. Joule ob-... 

France was a center for the development of thermodynamics, the study of heat and its conversion to other forms of energy. A few years before Ril-lieux s arrival in Paris, the French physicist Sadi Carnot had published his studies of steam engines and described the principles that became the second law of thermodynamics, placing fundamental limits on how efficiently heat can be used. Within a few years, James Prescott Joule of England would lay the basis for the first law of thermodynamics stating the equivalence of heat and energy. 

The first law of thermodynamics states that energy may be converted between forms, but cannot be created or destroyed. Joule was a superb experimentalist, and performed various types of work, each time generating energy in the form of heat. In one set of experiments, for example, he rotated small paddles immersed in a water trough and noted the rise in temperature. This experiment was apparently performed publicly in St Anne s Square, Manchester. Joule discerned a relationship between energy and work (symbol w). We have to perform thermodynamic work to increase the pressure within the tyre. Such work is performed every time a system alters its volume against an opposing pressure or force, or alters the pressure of a system housed within a constant volume. 

Joule obtained a much improved estimate of the Joule s equivalent of heat (Jjq = 4.15 J cal-1, within 1% of the modem value) and demonstrated its quantitative consistency for all these effects. Thus, Joule s name is rightly attached to the SI unit of energy, and he deserves to be considered the scientist most responsible for quantitative establishment of the first law of thermodynamics. 

One of the most intriguing achievements of the 19th century was James Joule s (1818-1889) determination of the mechanical equivalent of heat and, therefore, the first law of thermodynamics. There is a study of the background to this paper, through the analysis of Joule s work in electrochemistry.88... 

W. H. Cropper, James Joule s work in electrochemistry and the emergence of the first law of thermodynamics , Hist. Stud. Phys. Biol. Sci., 1988, 19, 1-15. 

Thermodynamics is primarily concerned with energy and entropy. Energy, also called internal energy ([/), comprises heat and work it is measured in joules (J). Work may be mechanical, electrical, chemical, interfacial, etc. It may be recalled that work generally equals force times distance (in N m = J) and that force equals mass times acceleration (in kg m s 2 = N). According to the first law of thermodynamics, the quantity of energy, i.e., heat + work + potential energy, is always preserved. 

In the boring experiment, work is done by the surroundings on the system (the brass cannon), the energy of the system rises and heat is also released to the surroundings (water bath). The First Law of Thermodynamics and the mechanical equivalent of heat (1 calorie = 4.184 joule) were established in 1843 by James Prescott Joule (1818-89). In order to raise the temperature of 1 gram of water by 1 °C (1 calorie), 4.184 joule of mechanical work, such as spinning paddles in water (Joule s experiment), is required. 

In this example we consider a variation of Joule s experiment a thermally insulated vessel contains 10 kg of water. The liquid is stirred by an impeller driven by a 1 kW motor. If the motor runs for 1 min and all of the work it produces is transferred to the liquid, analyze the experiment on the basis of the first law and report the relevant amounts of heat, work, and internal energy. 

Joule heating is named for James Prescott Joule, the first to articulate what is now Joule s law, relating the amount of heat released from an electrical resistor to its resistance and the charge passed through it. Joule s law gives the amount of... 

The first law is based mainly on the series of experiments carried out by Joule between 1843 and 1848. The most familiar of these experiments is the one in which he raised the temperature of a quantity of water, almost completely surrounded by an adiabatic wall, by means of a paddle which was operated by a falling weight. The result of this experiment was to show an almost exact proportionality between the amount of work expended on the water and the rise in its temperature. This result, considered on its own, is not very significant the really important feature of Joule s work was that the paddle-wheel experiments gave the same proportionality as was obtained in several other quite different methods of transforming work into the temperature rise of a quantity of water. These were as follows ... 

James Prescott Joule (1818-1889) An English physicist who discovered the relationship of heat to mechanical work (theory of conservation of energy, first law of thermodynamics). He collaborated from 1852 to 1856 with William Thomson (see box below). They developed the absolute scale of temperature and discovered the Joule-Thomson effect. Joule also frrund the relationship between the flow of current through a resistance and the dissipated heat, now called Joule s law. 

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