An electromagnetic wave of frequency \(1\times10^{14}\) hertz is propagating along z-axis. The amplitude of electric field is 4 V/m. If \(\varepsilon_0=8.8\times10^{-12}\ \mathrm{C^2/N\text{-}m^2}\), then average energy density of electric field will be:
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- \(35.2\times10^{-10}\ \mathrm{J/m^3}\)
- \(35.2\times10^{-11}\ \mathrm{J/m^3}\)
- \(35.2\times10^{-12}\ \mathrm{J/m^3}\)
- \(35.2\times10^{-13}\ \mathrm{J/m^3}\)
The Correct Option is C
Solution and Explanation
\(u_E=\frac14\times8.8\times10^{-12}\times16=35.2\times10^{-12}\ \mathrm{J/m^3}\).
The frequency is not needed.
Answer: (3) \(35.2\times10^{-12}\ \mathrm{J/m^3}\)
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