MCQ
In an electromagnetic wave the energy density associated with magnetic field will be
- A$\frac{1}{2}\,L{I^2}$
- ✓$\frac{{{B^2}}}{{2{\mu _0}}}$
- C$\frac{{1\,}}{2}{\mu _0}{B^2}$
- D$\frac{{1\,}}{2}\frac{{{\mu _0}}}{{{B^2}}}$
✓
Answer
Correct option: B.
$\frac{{{B^2}}}{{2{\mu _0}}}$
b
Energy density due to electric field $=\frac{1}{2} \epsilon E^{2}$
Energy density due to electric field $=\frac{1}{2} \epsilon E^{2}$
Energy density due to magnetic field $=\frac{1}{2} \frac{B^{2}}{\mu}$
since $\frac{E}{B}=c=\frac{1}{\sqrt{\epsilon \mu}}$
Energy density is equally contributed to by electric and magnetic fields.
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