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Academia - Collins - Pocket Scientific Dictionaries - Physics - English - French - Arabic - Letter 3_ B


bistable
stable f

Bistable. A transistor circuit can remain in one of two positions. It can be said that ordinary household circuit breakers are bistable, given that one of them can be in the ON or OFF position. However, outdoor lights are sometimes equipped with an automatic cut-off that cuts off the current after an appropriate time delay. It can be said that this constitutes an example of a “monostable circuit.” The drawing shows a bistable transistor circuit with a multivibrator.


block diagram
Schema in the block

Federal chart. A simplified way of presenting a circuit diagram that shows only the major functions of the component groups. The drawing shows the block diagram of a future radio.


Bohr, Niels
Bohr, Niels

Bor. Niels Bohr (1885 - (1962): A pioneering figure in the history of modern physics. His conception of the electron-proton in the atom led to the creation of the image we use today. Bohr accomplished fundamental work in the field of “quantum theory” and in 1922 he received the “ Nobel Prize. During World War II, Bohr worked on creating the atom bomb.


boiling point
point m d'ébullition

Boiling point. The temperature at which the vapor pressure of molecules escaping from the surface of a liquid becomes equal to atmospheric pressure and the normal boiling point of a pure liquid is when the external pressure is a standard atmospheric pressure equal to 760 mm of mercury. Thus, the normal boiling point of pure water is 100°C at a pressure of 760 mm. The boiling point decreases as the external pressure decreases, as is the case at the top of a high mountain. The boiling point increases when an impurity, such as table salt, is added.

Comparison between boiling and evaporation:

Boiling

It occurs at a certain temperature, which is the boiling point with respect to the prevailing external pressure.

The liquid gets inside, and bubbles appear.

Evaporation

It occurs at any temperature, but it increases with increasing temperature.

It only occurs at the surface of the liquid, and without bubbles.


bond energy
energie f de liaison

Binding energy. The energy required to separate the atoms from each other so that each is freed from the influence of the others, and thus from the energy that achieves the cohesion of the atoms among themselves.


Bourdon gauge
Manomètre m de Bourdon

Bourdon criterion. A type of manometers used to measure fluid pressure. As the pressure increases, the curved metal tube tends to straighten slightly, moving a pointer.


Boyle's law
Loif de Mariotte

Boyle's law. One of the three ideal gas laws. He says that the product of multiplying the volume of a fixed mass of gas by its pressure is constant at a fixed temperature. This law applies to any gas whose temperature is much higher than the boiling point. If a gas sample at a constant temperature moves from one state (P1, V1) to a second state (P2, V2),
P2, V2 = P1, V1. This means that if the pressure doubles, the volume is halved. . and so on . Pressure and volume are inversely proportional.

We can test this law simply with a syringe shown in Figure (a), and the result is:
The graphs in (b):

Gas sample
Known pressure