أكاديميا - كولنز - معاجم الجيب العلمية - الفيزياء - انكليزي - فرنسي - عربي الحرف ١_ b

Academia - Collins - Pocket Scientific Dictionaries - Physics - English - French - Arabic - Letter 1_ B


back emf
fcem

Opposite electromotive force.
See -electromagne.motor (electric), tic induction


background radiation
radiation f parasite

Background radiation. A radioactive substance found in almost all rocks of the Earth's crust. As they slowly decay, these materials release radiation. Cosmic radiation arrives from the sky to the surface of the Earth constantly, and as a result, the Geiger-Muller tube counts about one radiation pulse per second.

People believe that this background radiation may cause thousands of cancer deaths annually. It may also play a role in genetic changes (mutations).

To date, the background count has not increased much, if at all, as a result of nuclear weapons and power plants.


balance
balance f

balance . Balance . It is common to say that a body or a system is in a state of equilibrium when it is in equilibrium, that is, when the effects of the forces acting on it oppose each other such that they lead to an acceleration equal to zero.

A balance is a device that measures the mass or weight of an object by establishing a balance between forces. The balance of the arm balance and the balance of the crane are read when a balance occurs between the opposing torques of two masses in a gravitational field. Since it depends on the masses, these two machines measure the masses in practice, not the weight, and the readings are the same in any field that is not equal to zero.

As for the spring balance, it measures the weight of the body, as the body counteracts the tension or compression of the spring, and the reading varies according to the strength of the gravitational field. The spring balance measures gravity in newtons, and is often called the Newton balance.


bar magnet
Barreau mmagnétique

Magnetic rod. See magnetic field.magnet,


barometer
baromètre m

Atmospheric pressure gauge. A device used to measure air pressure. In a liquid barometer, there is a balance between air pressure and the pressure caused by a column of liquid. The liquid is usually mercury, because its high density means that the necessary pressure can be achieved with a moderately short column.

The standard height of a mercury barometer is 760 mm. Changes in the actual value over time help predict weather conditions.

But mercury is expensive and toxic, and the mercury barometer is large and difficult to use. The aneroid barometer does not have these problems, but it does not give readings with the same accuracy as a mercury barometer.


base voltage
tension f de la base

Base voltage. Al-Qaeda current.
See .transistors.


battery
battery f

battery . A group of single electric cells. Thus, the car battery consists of six voltage cells, each of which is 2 volts, which gives a total voltage of 12 volts during use.


beats
battement m

Two strikes. The effect of interference often occurs between two sound waves at a point in a medium, or between two alternating currents at a point in a circuit. The frequency of the beats is equal to the difference between the two frequencies, see the figure.

The frequency of two times one unit
Two-unit frequency
Frequency of 3 units