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

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


efficiency
rendement m

Return. The yield measures the ratio of useful energy output to the total energy input in all states of energy transfer. The output is often given as a percentage, and does not have a unit to represent it.

The energy input is not damaged, of course, but all the energy does not appear as desired. Thus, only 2% of the total energy used by a light bulb is converted into light. The car engine converts chemical energy into mechanical energy with a yield of about 25%. The most common energy waste is in the form of thermal energy and is equal to the return of a simple machine:

Work output (energy) / Work input (energy)
or
Force ratio/distance ratio


Einstein
Einstein

Einstein. Albert Einstein (1879 - 1955) A great modern physicist famous for his work on relativity (1905 and 1915). He also had many researches in other fields, such as: photo-electric effects, gravity, and quantum theory (see particle).


elasticity
elasticity f

Flexibility. Elastic matter obeys Hooke's law. This means that if we stretch or compress a sample, it deforms proportionally. It also returns to its original state when the stress stops at the elastic limit. However, if the stress is very great, the deformation becomes permanent, and the material becomes plastic. The drawing below shows the stress/strain curve (deformation curve) for a metal sample.

The reason for these effects is the forces between particles. Flexibility is important when making car springs, climbing ropes, etc.


electric field
Electric champ

Electric field. The area of ​​a place where electrical forces are exerted on any charges present. It is common to represent electric fields using lines of electric force or field lines. lines. We define such a line as the path taken by a free positive charge. These lines indicate the direction of the field and their closeness indicates the strength of the field.

The drawings below show, cross-sectionally, the fields around a single charge (a), two symmetrical charges (b), two asymmetrical charges (c), and two charged plates (d).

electricity
electrical f

electricity . The study of electric charge, whether it is moving (current electricity) or immovable (static electricity). The charge and its movement contain energy, and it is known that electricity is one of the main sources of energy.


electrochemistry
electrochemie f

Electrochemistry is the study of the transitions between electrical and chemical potential energies. We find in one direction that electrolysis is the use of current to obtain chemical reactions, and in the other direction the production of electrical reactions using chemical cells.


electrolysis
Electrolyse f

Electrolysis. The process in which current passes through an electrolyte. The latter is an ionic compound dissolved or molten, such as hydrogen chloride (HCL).

HCI = H++CI

If a voltage is placed between two electrodes in a substance, the electrolytes move toward the electrode carrying the opposite charge. When the positive ions reach the negative electrode (cathode), they gain electrons and become neutral:

2H++2e- → H2

In the same way, negative electrolytes become neutral at the anode (positive electrode):

2CI- → CI2 + 2e

Thus, the electrons actually pass through the electrolyte as they pass through the rest of the circuit. At the same time, there is a chemical reaction among the Messers. In this case, hydrogen gas bubbles appear at one of them, and at the other, chlorine gas bubbles appear.

Electrolysis is of great importance in industrial chemistry. It is also used in charging secondary cells (such as car batteries).


electromagnet
electro-aimant

Electromagnet. A device that acts like a magnet only when current passes through its coil. The core is usually made of iron.

See also bell, relay, and speaker.