- Home
- Standard 12
- Physics
8.Electromagnetic waves
easy
The vector $\vec E$ and $\vec B$ of an electromagnetic wave in vacuum are
A
along the same direction but of phase by $90^o$
B
along the same direction and in phase
C
perpendicular to each other and in phase
D
perpendicular to each other and out of phase by $90^o$
Solution
$S_{a v}=\frac{1}{2} \varepsilon_{0} E_{0}^{2} c=\frac{P}{4 \pi R^{2}}$
$\therefore \mathrm{E}_{0}=\sqrt{\frac{\mathrm{P}}{2 \pi \mathrm{R}^{2} \varepsilon_{0} \mathrm{c}}}$
$=\sqrt{\frac{3}{2 \times 3.14 \times 100 \times 8.86 \times 10^{-12} \times 3 \times 10^{8}}}$
$=1.34 \mathrm{\,V} / \mathrm{m}$
Standard 12
Physics
