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### PHYSICS DICTIONARY

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Josephson Junction

It is a device formed from sandwiching very thin insulator layer between two superconductors. There is continuous flow of electric current without influence of any external voltage in such devices, the effect which is named as Josephson Effect which was named after British scientist Brian Josephson who proposed it in 1962.

Joule Kelvin Effect

In physics, the Joule-Thomson effect or Joule-Kelvin effect describes the increase or decrease in the temperature of a real gas when it is allowed to expand freely at constant enthalpy (which means that no heat is transferred to or from the gas, and no external work is extracted). For each gas, there is a temperature of inversion above which the change is positive and below which it is negative.

Joule

It is SI unit of energy.

Joule’s Law of Heating

When a current of I amperes passes through a circuit of resistance R ohms for a time of t seconds then the heat produced is given by the relation H=I2Rt joules; The relation is known as the joule’s law of heating.

Joules Expansion

When a definite mass of a gas is expanded such that the external work done by the gas or on the gas is zero, neither the gas absorbs nor rejects any heat, then the expansion of gas is known as Joules expansion.

Joules Law (Gases)

Internal energy of an ideal gas only depends on its temperature ‘T’ and doesn’t depend on its volume ‘V’ and pressure ‘P’.

Joule-Thomson Effect

When a gas passes through an insulated porous plug from a constant high pressure to a constant low pressure, there is change in its temperature. This effect is called Joule-Thomson’s effect and the processes are called adiabatic throttling process.

Junction Diode

It is semiconductor device consisting of a single PN junction. It has a highly non linear current – voltage characteristic and is often used as a rectifying element.

Jupiter

Jupiter is the fifth planet from the Sun and by far the largest. Jupiter is more than twice as massive as all the other planets combined. The mass of Jupiter is 318 times that of Earth. It has orbit of 778,330,000 Km (5.20 AU) from Sun; Diameter of 142,984 km (equatorial); Mass of 1.900 x 1027 Kg.