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


ear
oreille f

permission . The auditory sense organ capable of detecting sound waves with frequencies ranging between about 20 Hz and 20 kHz (in humans). Incoming vibrations move the eardrum (a) back and forth, and the movement is transmitted through the middle ear by a series of small bones (b). The cochlea is located in the inner ear (c), and it is a coiled tube containing fluid. From this cochlea, the auditory nerve (d) transmits signals to the brain, and these signals are related to the frequency and height of the audio input.


earth
terre f

Grounding. If a body is connected to the ground by a carrier, it shares any charge it carries with it. Due to the large size of the Earth, this means that the grounded object cannot retain the charge. To ground something, we practically connect it to a metal plate buried in the ground, as in Figure (A). This drawing leads to the approved symbol for the grounding wire (B).

The green and yellow colored wire in the home use cable must be connected to the ground, which reduces the danger in the event of a malfunction, see three-pin plug. The ground connection provides protection for us. Without it, we could receive a fatal electric shock without the current supply being high enough to burn the magma.


Earth leakage circuit breaker disjuncteur m de terre

Earth leakage circuit breaker. Also called a residual current circuit breaker. See circuit breaker.


Earth's magnetism
Magnétisme m terrestre

Earth's magnetism. The Earth has a magnetic field that extends several thousand kilometers above the surface.

The reason may be due to the presence of a current inside the ground, mainly in the nickel-iron core. The Earth's field is similar to the field of a bar magnet whose south pole is located under the Earth's north pole.


echo
echo m

echo . The effect of reflection, for example, of sound, in which it appears that the radiation emanating from one source returns after a delay from another place, as an image of it.

The echo sounder (shown below) is very similar to radar and sonar. A similar technique is used to explore underground rock layers. In all these cases, the radiation emitted by the source is reflected. The delay of the returning echoes is analyzed with knowledge of the radiation speed in the medium.


eclipse
eclipse f

Eclipse. Eclipse: Because light travels in a straight line in a certain medium, we cannot see an object located directly behind an opaque object closer to us. The closest body eclipses (obscures) the other body.

If the moon passes completely between the earth and the sun, its shadow moves on the surface of the earth. People in the shadows see a solar eclipse. The eclipse is total for those in the shadow and partial for those in the penumbra. A lunar eclipse occurs when the Earth falls between the moon and the sun.

(without scale)
Lunar eclipse