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8.Electromagnetic waves
medium
The energy associated with electric field is $(U_E)$ and with magnetic field is $(U_B)$ for an electromagnetic wave in free space. Then
A
${U_E} = \frac{{{U_B}}}{2}$
B
$U_E\,>\,U_B$
C
$U_E\,<\,U_B$
D
$U_E\,=\,U_B$
(JEE MAIN-2019)
Solution
$\mathrm{B}=\frac{\mathrm{E}}{\mathrm{C}}$
$\Rightarrow \mathrm{U}_{\mathrm{E}}=\frac{1}{2} \varepsilon_{\mathrm{o}} \mathrm{E}^{2}$
$\mathrm{U}_{\mathrm{B}}=\frac{\mathrm{B}^{2}}{2 \mu_{0}}=\frac{\mathrm{E}^{2}}{2 \mu_{0} \mathrm{C}^{2}}=\frac{\mathrm{E}^{2}}{2 \mu_{0}}\left(\mu_{0} \varepsilon_{0}\right)=\mathrm{U}_{\mathrm{E}}$
Standard 12
Physics
