The electric field of plane electromagnetic wave of amplitude  2V/m varies with time, propagating along  z-axis. The average energy density of magnetic field  in J/m3  is equal to  x×10−12 J/m3. Then ‘x’  value is equal to (∈0=8.854×10−12 F/m)

# The electric field of plane electromagnetic wave of amplitude  2V/m varies with time, propagating along  z-axis. The average energy density of magnetic field  $\left(\text{in\hspace{0.17em}J}/{\text{m}}^{\text{3}}\right)$  is equal to  $x×{10}^{-12}\text{\hspace{0.17em}J}/{\text{m}}^{\text{3}}$. Then ‘x’  value is equal to (${\in }_{0}=8.854×{10}^{-12}\text{\hspace{0.17em}F}/\text{m}$)

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### Solution:

For an electro magnetic wave ,Average energy density due to electric field

=Average energy density due to magnetic field

$\begin{array}{l}=\frac{1}{4}{\epsilon }_{0}{E}_{0}^{2}\\ =\frac{1}{4}×8.85×{10}^{-12}×2×2\end{array}$

$\therefore x=8.85$  Register to Get Free Mock Test and Study Material

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