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A plane electromagnetic wave travels in a medium of relative permeability $1.61$ and relative permittivity $6.44$. If magnitude of magnetic intensity is $4.5 \times 10^{-2} \;Am ^{-1}$ at a point, what will be the approximate magnitude of electric field intensity at that point$?$
(Given : permeability of free space $\mu_{0}=4 \pi \times 10^{-7}\;NA ^{-2}$, speed of light in vacuum $c =3 \times 10^{8} \;ms ^{-1}$ )
$16.96\; Vm ^{-1}$
$2.25 \times 10^{-2}\; Vm ^{-1}$
$8.48\; Vm ^{-1}$
$6.75 \times 10^{6} \;Vm ^{-1}$
Solution
$\mu_{ I }=1.61 \quad \epsilon_{ I }=6.44$
$B =4.5 \times 10^{-2}$
$E =$ $?$
$C =\frac{1}{\sqrt{\mu_{0} \epsilon_{0}}} V =\frac{1}{\sqrt{\mu \epsilon}}$
$\frac{ C }{ V }=\sqrt{\mu_{ r } \epsilon_{ r }}=\sqrt{1.61 \times 6.44}$
$\frac{E}{B}=V=\frac{3 \times 10^{8}}{\sqrt{1.61 \times 6.44}}=9.32 \times 10^{7} m / s$
$E =4.5 \times 10^{-2} \times 9.32 \times 10^{7}$
$=4.2 \times 10^{6}$
