FablabSU

<fc #6495ed>Nous avons</fc>

$\large{{e}={\frac{{\lambda}}{{4}.{\Delta}{n}}} \quad avec\quad {\lambda}={c}.{T}={\frac{{c}}{{f}}}}$

$\large{{e}={\frac{{c}}{{f}.{4}.({n}_{e}-{n}_{0})}}}$

<fc #6495ed>avec</fc>

$\large{{n}_{e}={n}_{plexiglas}={1,50}}$

$\large{{n}_{0}={n}_{air}={1,0002926}}$

<fc #6495ed>ainsi</fc>

$\large{{e}={6,11}.{10}^{-3}{m}}$

<fc #6495ed>de même</fc>

$\large{{T}={\tau}_{1}-{\tau}_{2} \quad avec\quad {\tau}_{1}={\frac{{e}_{1}}{{c}_{plexiglas}}},\quad {\tau}_{2}={\frac{{e}_{2}}{{c}_{plexiglas}}}+{\frac{{e}_{1}-{e}_{2}}{{c}_{air}}} \quad et\quad {e}={e}_{1}+{e}_{2}}$

$\large{{T}={\frac{{e}_{1}}{{c}_{plexiglas}}}-({\frac{{e}_{2}}{{c}_{plexiglas}}}+{\frac{{e}_{1}-{e}_{2}}{{c}_{air}}})}$

$\large{{T}={\frac{({e}_{1}-{e}_{1})}{{c}_{plexiglas}}}-{\frac{({e}_{1}-{e}_{2})}{{c}_{air}}}}$

$\large{{T}=({e}_{1}-{e}_{2}).[{\frac{{1}}{{c}_{plexiglas}}}-{\frac{{1}}{{c}_{air}}}]}$

<fc #6495ed>Nous obtenons ainsi</fc>

$\large{{({e}_{1}-{e}_{2})}={\frac{{T}}{[{\frac{{1}}{{c}_{plexiglas}}}-{\frac{{1}}{{c}_{air}}}]}}}$

<fc #6495ed>donc</fc>

$\large{{e}_{1}={\frac{{e}}{{2}}}+{\frac{{T}}{{2}.[{\frac{{1}}{{c}_{plexiglas}}}-{\frac{{1}}{{c}_{air}}}]}}={\frac{{e}}{{2}}}+{\frac{{1}}{{2}.{f}.[{\frac{{1}}{{c}_{plexiglas}}}-{\frac{{1}}{{c}_{air}}}]}}}$

$\large{{e}_{2}={\frac{{e}}{{2}}}-{\frac{{T}}{{2}.[{\frac{{1}}{{c}_{plexiglas}}}-{\frac{{1}}{{c}_{air}}}]}}={\frac{{e}}{{2}}}-{\frac{{1}}{{2}.{f}.[{\frac{{1}}{{c}_{plexiglas}}}-{\frac{{1}}{{c}_{air}}}]}}}$

<fc #4682b4>Lien du fichier</fc> → https://www.dropbox.com/s/tmktkhb18fd8e6b/L%C3%A9vitation%20acoustique.gan?dl=0