Calculate the average total energy density of an electromagnetic wave coming from the sun that has the RMS value of electric field as 720 N C- 1 .

Question

Calculate the average total energy density of an electromagnetic wave coming from the sun that has the RMS value of electric field as 720 N C- 1 . (A) 3.3× 10- 3 J m- 3 (B) 4.58× 10- 6 J m- 3 (C) 6.37× 10- 9 J m- 3 (D) 81.35× 10- 12 J m- 3 .

Tardigrade Admin · Accepted Answer

Total average energy density of electromagnetic wave is

U_{a v} = \frac{1}{2} ε_{0} E_{r m s}^{2} + \frac{1}{2 μ _{0}} B_{r m s}^{2} = \frac{1}{2} ε_{0} E_{r m s}^{2} + \frac{1}{2 μ _{0}} (\frac{E _{r m s}^{2}}{c ^{2}}) (∵ B_{r m s} = \frac{E _{r m s}}{c}) = \frac{1}{2} ε_{0} E_{r m s}^{2} + \frac{1}{2 μ _{0}} E_{r m s}^{2} ε_{0} μ_{0} (∵ c = \frac{1}{μ _{0} ε _{0}}) = \frac{1}{2} ε_{0} E_{r m s}^{2} + \frac{1}{2} ε_{0} E_{r m s}^{2} = ε_{0} E_{r m s}^{2} (∵ 0^{- 12} \times (720)^{2} = 4.58 \times 1 0^{- 6} J m = 8.85 \times 1 0^{- 3}

Q. Calculate the average total energy density of an electromagnetic wave coming from the sun that has the $RMS$ value of electric field as $720 N C^{- 1}$ .

$3.3 \times 1 0^{- 3} J m^{- 3}$

$4.58 \times 1 0^{- 6} J m^{- 3}$

$6.37 \times 1 0^{- 9} J m^{- 3}$

$81.35 \times 1 0^{- 12} J m^{- 3}$ .

Q. Calculate the average total energy density of an electromagnetic wave coming from the sun that has the RMS value of electric field as 720NC−1 .

3.3×10−3Jm−3

4.58×10−6Jm−3

6.37×10−9Jm−3

81.35×10−12Jm−3 .

Q. Calculate the average total energy density of an electromagnetic wave coming from the sun that has the $RMS$ value of electric field as $720 N C^{- 1}$ .

$3.3 \times 1 0^{- 3} J m^{- 3}$

$4.58 \times 1 0^{- 6} J m^{- 3}$

$6.37 \times 1 0^{- 9} J m^{- 3}$

$81.35 \times 1 0^{- 12} J m^{- 3}$ .