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


absolute zero
Zero m absolu

Absolute zero. The lowest possible temperature, meaning all the heat is removed.” Its symbol is OK (ie zero 0 on the Kelvin scale). It is equal to absolute zero - 273 m. Note that the degree sign is not used on the Kelvin scale.

absorption
absorption f

absorption. When a ray passing through one medium meets the surface of another medium, three things can happen:
a) The ray can bounce back to the first medium (reflection).

b) Or it can be transmitted through the second medium, perhaps in a new direction (refraction).

(c) Or it can disappear (absorption).

Reflected beam
Middle surface 2
Middle 1
A falling beam
absorption
Refracted ray

When the surface absorbs the beam, the energy must appear in another form. In most cases, the temperature rises, and it is related to thermal energy. Other radiation may appear, such as X-rays, from cathode rays, light from ultraviolet radiation (fluorescence), and electrons from light rays.
(photoelectric effect)


absorption of atomic radiation absorption m de radiation atomique

Absorption of atomic radiation. Alpha particles are easily absorbed and stopped by a thick piece of paper or a few centimeters of air. Beta particles can be stopped by a few millimeters of aluminum. As for gamma radiation, it is mostly stopped by lead. See atomic radiations.

absorption of colour
Absorption of the color

Color absorption. This is what the filter does. The pure red filter absorbs all light radiation other than shades of red, and therefore only red light passes through it. Hence, the intensity of the light coming out of the filter is less than the intensity of the light falling on it.

absorption of heat
Absorption of the chaleur

Heat absorption. Dark, matte surfaces absorb (or emit) heat (infrared radiation) easily. Bright, light objects do not absorb (or emit) heat as much as dark objects do.

acceleration(a)
accélération f

Acceleration. Change of body speed 7 per unit time. Its unit in the International System of Units (SI) is the meter per second multiplied by the second m/s2.
v - u / t = a
Where u is the initial velocity and v is the final velocity.
An object accelerates if its speed and/or direction changes
His movement. See, for example, centripetal force.

There is an important relationship between the acceleration a of a body of mass m when a net force F is applied to it from the outside.
One of Newton's laws of motion is that a=F/m.
See also free fall and equations of motion.

Note that acceleration is the slope of the velocity/time graph at any instant. Note also that we sometimes call negative acceleration deceleration and retardation.

accuracy
precision f

Accuracy. How close the measurement is to the correct value.
It is important to provide numerical answers for the number of numbers that can be correct, taking into account the expected accuracy of any information used or any experimental readings. Thus, in an experiment to find the specific heat capacity, the temperatures could be 24.0 and 48.5 degrees Celsius (reading to the nearest half degree). However, it is expected that experimental errors will make the readings correct only to the closest degree. Mass readings can be 79.24 g and 210.42 g. Accuracy is limited by the accuracy of the weakest readings – in this case temperatures. Here, it is not possible to present the results of the entire experiment with more than two significant figures at best, especially since the errors are cumulative. After processing the readings with a calculator, the seven- or eight-digit answers must be reduced to two significant figures in this example), preferably given in standard form. Accuracy in an experiment can be improved by:

A) Repeat the readings several times and take their average.

b) Taking measures to reduce expected experimental errors, modify the experiment, etc.

C) Using more sensitive devices, such as a micrometer instead of a ruler, for example.
See also precision.