أكاديميا - كولنز - معاجم الجيب العلمية - الفيزياء - انكليزي - فرنسي - عربي الحرف ٢_ n

Academia - Collins - Pocket Scientific Dictionaries - Physics - English - French - Arabic Letter 2_ N


nodes and antinodes
nœads and antinœuds mpl

Nodes and bellies. When there are standing waves in the system, there is no oscillation at some points, and the amplitude is constantly zero. These points are called nodes. There are points between those points, “antinodes,” where there is always a maximum amplitude of vibration.

Note: The node is where there is no offset. Thus, a stretched string (see sound sources) vibrating with three cycles of standing waves has nodes at points N and bellies at points A.
See also interference.


noise. noise
bruit f

Noise. An uncomfortable sound for hearing is caused in most cases
Cases indicate that it is a mixture of frequencies that are not closely related to each other. (“Frequencies harmonize” if they are in small proportions to each other). Therefore, noise is a mixture of random frequencies. The term is used in this sense in electronics and other fields, as well as the field of sound.

White noise contains a mixture of all frequencies in a range. For example, the background whistle or hiss heard on radios or televisions.


nuclear power
Nuclear energy

Nuclear Energy . Providing useful energy resulting from nuclear reactions. The power station is built around a nuclear reactor. The only types of reactors in operation so far are fission ones. In theory, fusion is more effective, safer, and less expensive, and research is still ongoing with the aim of successfully using this interaction in practice.

In a fission pile nuclear reactor, a controlled chain reaction takes place at a constant rate. The kinetic energy of the particles generated in each fission is transformed into a rise in temperature. The coolant removes this thermal energy by converting it into steam that drives turbines connected to a generator.

The central reactor in the thermal reactor has two components, in addition to the fuel used. The moderator must slow the neutrons generated by each fission to a speed low enough to cause more fission. Graphite is commonly used for this purpose. Control rods, which are often boron, safely absorb the neutrons and are raised and lowered in the core to keep the reaction at its correct level.

Finally, there is a thick shield of steel and cement around the reactor, preventing inappropriate leakage of radiation from the core that would expose people outside.
To danger.

The simplified drawing below shows a standard-type fission reactor. The fuel for this thermal reactor is enriched uranium - with a high content of the active isotope 235U. The breeder reactor does not need a moderator and can operate with normal uranium instead of enriched uranium. Added here to the normal fission of 235U is the energy transfer from the confinement of 238U
For neutrons. This capture produces plutonium, a nuclear fuel such as 235U.

Many people are concerned about the safety of nuclear reactors, especially since waste disposal is still not completely safe. There are critics who express their concern about the wisdom of using nuclear reactors, and they fear terrorist attacks on nuclear plants that may lead to the leakage of dangerous materials, or to the theft of plutonium. There is no doubt that a country can manufacture fuel for an atom bomb using a power reactor.


nucleon
nuclear m

Nucleus: A mass particle found in the nuclei of atoms. It may be a proton or a neutron.