أكاديميا - كولنز - معاجم الجيب العلمية - الفيزياء - انكليزي - فرنسي - عربي الحرف ٧_ c

Academia - Collins - Pocket Scientific Dictionaries - Physics - English - French - Arabic Letter 7_ C


conduction, electrical
Electrical conduction

Electric transportation. The process of transferring a charge across a medium. There is also a transfer of energy in almost all cases. The “carrier” is a material capable of passing the charge easily. As for the semiconductor, it is good in transportation. Insulators do not allow charge transfer except when the applied voltage is very high. The voltage applied to a sample involves making one end positive compared to the other end. If the sample contains free moving charges, it is forced to move towards the end that has the opposite charge.

Metals and carbon are the only solids through which charge can pass easily. This is due to the metal containing many (negative) electrons that are not bound to other particles and are therefore free to move. The voltage causes these electrons to accelerate. When they move, they collide with each other and with the positive cores that form the body of the metal. The collisions slow down the movement of the electrons, so they show resistance to the current and there is a transfer of energy that leads to an increase in temperature.
See fuse.

The current, which is the flow of charge per second, depends on the voltage and resistance. See Ohm's law.

Note that it is natural to give the current a direction that goes from positive to negative. In many cases, such as those above, the current actually consists of negative charge moving in the opposite direction.

There are other conductive fluids, in addition to liquid metals. These fluids contain negative and positive electrolytes, and we call them electrolytes. The current passing through it has chemical effects.
Look . electrolysis.

Gases are insulating. However, the voltage
Relatively low gives current at low pressure. The transfer of energy is into radiation, such as light. This discharge is used through gases in neon and fluorescent lamps. Here also the process is a process of transfer of electrolytes.
And vacuum is an insulator. If the voltage is high enough, the electrons are expelled from the negative electrode and move at high speed into the empty space. See cathode rays.

Condition----Medium----Transportation method

Solid ---- metal ----- electrons
Semiconductor ---- electrons

Liquid ---- metal ----- electrons
Electrolyte ----- electrolytes

Gas ---- ----- Electrolytes and electrons

Vacuum ---- ------ Electrons


conduction, thermal
conduction of thermometer

Thermal transfer. The transfer of energy from particle to particle in matter. Compare with convection, radiation, and evaporation. Materials differ in their ability to be transported in this way. Non-metals are very weak conductors, and we use them for thermal insulation. As for metals, they are good heat conductors, containing “a gas of free-moving electrons that carries energy quickly from high-temperature points.”


conservation of energy
energy conservation

energy saving . See energy.


control rod
Barre for control

Control rod. See nuclear power.


convection
convection f

Pregnancy . The transfer of energy through a fluid, which involves moving against the gravity of particles with a higher temperature, the latter of which are less dense, so they are displaced and replaced by cooler, denser particles.
Compare with conduction, thermal, radiation and evaporation. Convective “currents” appear as cold particles replacing hot ones. Winds and breezes form convection currents in the atmosphere.