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Between 1840 and 1843, Joule carefully studied the heat produced by an electric current. From this study, he developed Joule's laws of heating, the first of which is commonly referred to as the Joule effect. Joule's first law expresses the relationship between heat generated in a conductor and current flow, resistance, and time. [1]
The energy required to accelerate a 1 kg mass at 1 m/s 2 through a distance of 1 m. The kinetic energy of a 2 kg mass travelling at 1 m/s, or a 1 kg mass travelling at 1.41 m/s. The energy required to lift an apple up 1 m, assuming the apple has a mass of 101.97 g. The heat required to raise the temperature of 0.239 g of water from 0 °C to 1 ...
The electrostatic potential energy, U E, of one point charge q at position r in the presence of an electric field E is defined as the negative of the work W done by the electrostatic force to bring it from the reference position r ref [note 1] to that position r. [1] [2]: §25-1
List of orders of magnitude for energy; Factor (joules) SI prefix Value Item 10 −34: 6.626 × 10 −34 J: Energy of a photon with a frequency of 1 hertz. [1]8 × 10 −34 J: Average kinetic energy of translational motion of a molecule at the lowest temperature reached (38 picokelvin [2] as of 2021)
A moderate energy density would be 1.6 to 3 calories per gram (7–13 kJ/g); salmon, lean meat, and bread would fall in this category. Foods with high energy density have more than three calories per gram (>13 kJ/g) and include crackers, cheese, chocolate, nuts, [ 10 ] and fried foods like potato or tortilla chips.
Some food processing equipment may make use of Joule heating: running a current through food material (which behave as an electrical resistor) causes heat release inside the food. [2] The alternating electrical current coupled with the resistance of the food causes the generation of heat. [3] A higher resistance increases the heat generated.
The watt (symbol: W) is the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m 2 ⋅s −3. [1] [2] [3] It is used to quantify the rate of energy transfer.
It is also an SI derived unit of molar thermodynamic energy defined as the energy equal to one joule in one mole of substance. [1] [2] For example, the Gibbs free energy of a compound in the area of thermochemistry is often quantified in units of kilojoules per mole (symbol: kJ·mol −1 or kJ/mol), with 1 kilojoule = 1000 joules. [3]