Question 157: EM waves

Question

The $$rms$$ value of the electric field of the light coming from the Sun is $$720$$ $$N/C.$$ The average total energy density of the electromagnetic wave is

Accepted Answer

$${E_{rms}} = 720$$
The average total energy density
$$ = {1 \over 2}{ \in _0}\,E_0^2 = {1 \over 2}{ \in _0}{\left[ {\sqrt 2 {E_{rms}}} ight]^2} = { \in _0}\,E_{rms}^2$$
$$ = 8.85 	imes {10^{ - 12}} 	imes {\left( {720} ight)^2}$$
$$ = 4.58 	imes {10^{ - 6}}\,J/{m^3}$$

Answer

$$4.58 	imes {10^{ - 6}}\,J/{m^3}$$

Answer

$$6.37 	imes {10^{ - 9}}\,J/{m^3}$$

Answer

$$81.35 	imes {10^{ - 12}}\,J/{m^3}$$

Answer

$$3.3 	imes {10^{ - 3}}\,J/{m^3}$$

EM waves

The $rms value of the electric field of the light coming from the Sun is 720 N/C.$ The average total energy density of the electromagnetic wave is

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