JEE Mains · Physics · STD 12 - 8. Electromagnetic waves
The electric field in an electromagnetic wave is given as \(\vec{E}=20 \sin \omega\left(t-\frac{x}{c}\right) \vec{j} NC ^{-1}\) Where \(\omega\) and \(c\) are angular frequency and velocity of electromagnetic wave respectively. The energy contained in a volume of \(5 \times 10^{-4}\, m ^3\) will be \(.....\times 10^{-13}\,J\) (Given \(\varepsilon_0=8.85 \times 10^{-12}\,C ^2 / Nm ^2\) )
- A \(28.5\)
- B \(17.7\)
- C \(8.85\)
- D \(88.5\)
Answer & Solution
Correct Answer
(C) \(8.85\)
Step-by-step Solution
Detailed explanation
\(\overrightarrow{ E }=20 \sin \omega\left( t -\frac{ x }{ C }\right) \hat{ j } / C\) Average energy density of an em wave \(=\frac{1}{2} \epsilon_0 E_0^2\) \(\text { Energy stored }=\left(\frac{1}{2} \epsilon_0 E _0^2\right)(\text { volume })\)…
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