\(u =\frac{1}{2} \varepsilon_{0} E _{ rms }^{2}+\frac{1}{2 \mu_{0}} B _{ rms }^{2}\)
\(= \frac{1}{2} \varepsilon_{0} E _{ rms }^{2}+\frac{1}{2 \mu_{0}} \frac{ E _{ rms }^{2}}{ c ^{2}} \quad\left(\because B _{ rms }=\frac{ E _{ rms }}{ c }\right)\)
\(= \frac{1}{2} \varepsilon_{0} E _{ rms }^{2}+\frac{\varepsilon_{0} \mu_{0} E _{ rms }^{2}}{2 \mu_{0}} \left(\because c ^{2}=\frac{1}{\varepsilon_{0} \mu_{0}}\right)\)
\(= \frac{1}{2} \varepsilon_{0} E _{ rms }^{2}+\frac{1}{2} \varepsilon_{0} E _{ rms }^{2}\)\(=\varepsilon_{0} E _{ rms }^{2}\)
\(= 8.85 \times 10^{-12} \times(720)^{2}\)
\(= 4.58 \times 10^{-6} J / m ^{3}\)
વિકિરણ $(I)$ | વિકિરણ $(II)$ |
$(a)$ માઇક્રોવેવ | $(i)$ $100\,m$ |
$(b)$ ગેમા કિરણ | $(ii)$ $10^{-15} m$ |
$(C)$ રેડિયો તરંગ | $(iii)$ $10^{-10} m$ |
$(d)$ $x-$ કિરણ | $(iv)$ $10^{-3} m$ |