L’AIR SUR VOTRE LONGUEUR D’ONDE
Longueur maximale équivalene t (m) 15 20 20 25 Dénivelé maximal (m) 10 Câble de ommunicac tion (m) 3 x 1,5 + T 3 x 1,5 + T 3 x 1,5 + T 3 x 2,5 + T Câble d’alimentation U,E, 2 x 2,5 + T Longueur préchargée (m) 5 UNITÉ INTÉRIEURE
Physique & Chimie 2 BAC
: Longueur d'onde dans le vide = ???? = ???? λ : Longueur d'onde un milieu matériel Remarque La fréquence de l’onde lumineuse ne dépend pas du milieu de propagation Domaine des ondes lumineuses visibles: ????∈[ ; ] ii Diffraction d'une onde lumineuse monochromatique 1) Aspect ondulatoire de la lumière
PHYSIQUE Unité :1 PROPAGATION DUNE ONDE-ONDES PROGRESSIVES
Unité :1 PROPAGATION D'UNE ONDE-ONDES PROGRESSIVES On veut retrouver expérimentalement la longueur d'onde λ D de la radiation monochromatique du LASER d'un lecteur DVD On utilise pour cela le montage de la figure ci contre : a étant le diamètre du fil, l’écart angulaire
PHYSIQUE / Unité :1 PROPAGATION DUNE ONDE-ONDES PROGRESSIVES
se propagent le long d’une corde élastique à partir de son extrémité S, avec la célérité v=8,0m s-1 1- Calculer la longueur d’onde de l’onde qui se propage sur la corde 2- Comparer le mouvement de la source vibratoire le mouvement d’un point A situé à 32 cm de S et celui d’un point B placé à 40 cm de S
Observer: Chapitre 4 : analyse spectrale
- A est sans unité -6(Ç): coefficient d'absorption molaire qui dépend du solvant de la température et de la longueur d'onde Unité légale: m-1 mol L - L(m): épaisseur de solution traversée - C (mol m-3) : concentration de la solution - k constante pour une longueur d’onde fixe exprimée en _____ Remarque :
Fiches de revision de physique-chimie´ pour la classe de
D eterminer si est un multiple entier ou demi-entier de la longueur d’onde D eterminer la distance entre deux franges cons ecutives de m^eme nature sur une gure d’interf erences Calculer l’interfrange Exploiter l’analyse spectrale d’un son musical Savoir que les gures d’interf erences propres a chaque longueur d’onde se
FiberMASTER™ Kit fibre optique monomode & multimode
Longueur d’onde sélectionnée Valeurs de perte / puissance reçue Unités dBm, mW, dB Ecran LCD avec valeurs en dB / dBm / mW Adaptateur universel 2,5mm Sélecteur dBm / mW Interrupteur Interrupteur Fonction de calibration des cordons de mesure Longueurs d’onde 850, 1300, 1310, 1550nm Adaptateurs SC, ST et FC interchangeables
TransfertRadiatif BilanÉnergétique ofRadiation 4
d’onde Ainsi,uneluminancespectrale ????s’exprimeraenW⋅m????????⋅μm????????⋅sr????????,et ???? enW ⋅ m ???????? ⋅ s ⋅ sr ???????? 1 4Absorptionettransmission
DST : Physique-Chimie
ou` λest la longueur d’onde de chaque radiation et hest la constante de Planck et cla c´el´erit´e de la lumi`ere Les longueurs d’onde du spectre du Soleil vont approximativement de 200 nm a plus de 3000 nm Un semi-conducteur comme le silicium est capable d’absorber des radiations de longueurs d’onde allant de 300 a 1200 nm
[PDF] longueur d'un microbe
[PDF] longueur d'un segment dans l'espace
[PDF] longueur d'une molecule
[PDF] Longueur de cloture
[PDF] Longueur de ficelle
[PDF] Longueur de l'hypoténuse
[PDF] Longueur de la laisse
[PDF] longueur de perche
[PDF] longueur définition
[PDF] longueur des intestins
[PDF] longueur des phrases effet
[PDF] longueur des tubes de l'atomium
[PDF] longueur du mur de berlin
[PDF] Longueur du segment avec l'unité u
114Radiative Transfer
wavelengths and frequencies, the energy that it carries can be partitioned into the contributions from various wavelength (or frequency or wave number) bands. For example, in atmospheric science the term shortwave 2 (??4?m) refers to the wavelength band that carries most of the energy associated with solar radia- tion and longwave( ??4?m) refers to the band that encompasses most of the terrestrial (Earth-emitted) radiation. In the radiative transfer literature, the spectrum is typically divided into the regions shown in Fig. 4.1. The relatively narrow visibleregion, which extends from wavelengths of 0.39 to 0.76 ?m, is defined by the range of wavelengths that the human eye is capa- ble of sensing.Subranges of the visible region are dis- cernible as colors: violet on the short wavelength end and red on the long wavelength end.The term mono- chromaticdenotes a single color (i.e.,one specific fre- quency or wavelength).The visible region of the spectrum is flanked by
ultraviolet(above violet in terms of frequency) and infrared(below red) regions. The near infrared region, which extends from the boundary of the visi- ble up to 4 ?m, is dominated by solar radiation, whereas the remainder of the infrared region is dom- inated by terrestrial(i.e., Earth emitted) radiation: hence, the near infrared region is included in the term shortwave radiation. Microwave radiation is not important in the EarthÕs energy balance but it is widely used in remote sensing because it is capable of penetrating through clouds.4.2 Quantitative Description
of Radiation The energy transferred by electromagnetic radiation in a specific direction in three-dimensional space at a specific wavelength (or wave number) is called monochromatic intensity(or spectral intensityor monochromatic radiance) and is denoted by the symbol I (or I ). Monochromatic intensity is expressed in units of watts per square meter per unit arc of solid angle, 3 per unit wavelength (or per unit wave number or frequency) in the electromagnetic spectrum.The integral of the monochromatic intensity over
some finite range of the electromagnetic spectrum is called the intensity(or radiance) I, which has units of W m ?2 sr ?1 (4.3) For quantifying the energy emitted by a laser, the interval from 1 to ? 2 (or ? 1 to ? 2 ) is very narrow, whereas for describing the EarthÕs energy balance, it encompasses the entire electromagnetic spec- trum. Separate integrations are often carried out for the shortwave and longwave parts of the spectrum corresponding, respectively, to the wavelength ranges of incoming solar radiation and outgoing ter- restrial radiation. Hence, the intensity is the area under some finite segment of the the spectrum of monochromatic intensity (i.e., the plot of I as a function of ?, or I as a function of ?, as illustrated in Fig. 4.2).Although I
and I both bear the name monochro- matic intensity, they are expressed in different units.The shapes of the associated spectra tend to be
somewhat different in appearance, as will be appar- ent in several of the figures later in this chapter. In Exercise 4.13,the student is invited to prove that (4.4)I 2 I I? 2 1 I d?? 2 1 I d? 2The term shortwaveas used in this book is not to be confused with the region of the electromagnetic spectrum exploited in shortwave
radio reception,which involves wavelengths on the order of 100 m,well beyond the range of Fig.4.1. 3The unit of solid angle is the dimensionless steradian(denoted by the symbol ?) defined as the area ?subtended by the solid angle
on the unit sphere.Alternatively,on a sphere of radius r,???r 2 .Exercise 4.1 shows that a hemisphere corresponds to a solid angle of 2? steradians.Fig. 4.1The electromagnetic spectrum.
ray ons X ultraviolet visible proche infrar ouge infrar ouge micro -onde longueur d'onde 0.01 101105 10 4 10 3
1001010.1
µ m
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4.4 Physics of Scattering and Absorption and Emission123
convenient to express the rate of scattering or absorption in the form (4.17) where is the density of the air,ris the mass of the absorbing gas per unit mass of air, and k is the mass absorption?coefficient,which has units of m 2 kg 1In the aforementioned expressions the products
N K and rk are volume?scattering, absorption, or extinction?coefficients, depending on the context, and have units of m 1 . The contributions of the various species of gases and particles are additive (i.e.,K N(K 1 N 1 1 (K 2 N 2 2 ....), as are the contributions of scattering and absorption to the extinction of the incident beam of radiation;i.e., (4.18)4.4.1 Scattering by Air Molecules
and ParticlesAt any given place and time, particles including
aerosols with a wide variety of shapes and sizes, as well as cloud droplets and ice crystals, may be pres- ent. Nonetheless it is instructive to consider the case of scattering by a spherical particle of radius r, for which the scattering, absorption, or extinction efficiency K in (4.16) can be prescribed on theK (absorption)K (extinction)K (scattering)dI I rk ds basis of theory, as a function of a dimensionless size parameter (4.19) and a complex index?of?refractionof the particles (mm r im i ), whose real part m r is the ratio of the speed of light in a vacuum to the speed at which light travels when it is passing through the particle. Figure 4.11 shows the range of size param- eters for various kinds of particles in the atmos- phere and radiation in various wavelength ranges. For the scattering of radiation in the visible part of the spectrum,xranges from much less than 1 for air molecules to 1 for haze and smoke particles to1 for raindrops.
Particles with x1 are relatively ineffective at
scattering radiation. Within this so-called Rayleigh scatteringregime the expression for the scattering efficiency is of the form (4.20) and the scattering is divided evenly between the forward and backward hemispheres, as indicated in Fig. 4.12a. For values of the size parameter compara- ble to or greater than 1 the scattered radiation is directed mainly into the forward hemisphere, as indi- cated in subsequent panels.Figure 4.13 shows K
as a function of size parame- ter for particles with m r1.5 and a range of values
of m i . Consider just the top curve that correspondsK 4 x2 r I - dI dzds = sec dzI Fig. 4.10Extinction of incident parallel beam solar radia- tion as it passes through an infinitesimally thin atmospheric layer containing absorbing gases and/or aerosols. Radar météo Rayo n t solaireRayontterrestre
110102 10 3 10 4 10 5 10 4 10 3 10 2 10 1 10 1 10 2 10 3
Optique géométrique
Diffusion de Mie
Diffusion Rayleigh
PluieBruine
Gouttes
de nuagesPoussière
fuméeMolécules
de l'air r rr m) x 1 (µ m)P732951-Ch04.qxd 9/12/05 7:41 PM Page 123
124Radiative Transfer
to m i ?0 (no absorption). For 1?x?50, referred to as the Mie 10 scattering regime, K exhibits a damped oscillatory behavior, with a mean around avalue of 2, and for x?50, the range referred to asthe geometric optics regime, the oscillatory behavior
is less prominent and K 2. Exercise 4.9Estimate the relative efficiencies with which red light ( ?0.64?m) and blue light ?0.47?m) are scattered by air molecules.Solution:From (4.20)
Hence, the preponderance of blue in light scattered by air molecules, as evidenced by the blueness of the sky on days when the air is relatively free from aerosols.Figure 4.14 shows an example of the coloring of
the sky and sunlit objects imparted by Rayleigh scat- tering. The photograph was taken just after sunrise. Blue sky is visible overhead, while objects in the foreground, including the aerosol layer, are illumi- nated by sunlight in which the shorter wavelengths (bluer colors) have been depleted by scattering along its long,oblique path through the atmosphere.Ground-based weather radars and remote sensing
of rainfall from instruments carried aboard satellites exploit the size strong dependence of scattering efficiency Kupon size parameter xfor microwave radiation in the 1- to 10-cm wavelength range inci- dent upon clouds with droplet radii on the order of millimeters. In contrast to infrared radiation, whichK(blue)K(red)?
0.64 0.47 4 ?3.45 (a) (b) (c)Faisceau incident
Avant Fig. 4.12Schematic showing the angular distribution of the radiation at visible (0.5 ?m) wavelength scattered by spherical particles with radii of (a) 10 ?4 ?m, (b) 0.1?m, and (c) 1?m.The forward scattering for the 1-
?m aerosol is extremely large and is scaled for presentation purposes. [Adapted from K. N. Liou, An Introduction to Atmospheric Radiation, AcademicPress, p. 7 (2002).]
10Gustav Mie(1868Ð1957) German physicist. Carried out fundamental studies on the theory of electromagnetic scattering and kinetic
theory. 0Scattering efficiency K
Size parameter x1 5 10 50 1001
2345m i = 1m i = 0.1m i = 0.01m i = 0