Question 144: EM waves

Question

The energy associated with electric field is (U
E
) and with magnetic field is (U
B
) for an electromagnetic wave in free space. Then :

Accepted Answer

Energy density of magnetic field (U
B
) = $${{{B^2}} \over {2{\mu _0}}}$$
Also,
Energy density  of electric field
U
E
= $${1 \over 2}$$ $$\varepsilon $$
0
E
2
= $${1 \over 2}$$ $$\varepsilon $$
0
B
2
C
2
[as    $${E \over B}$$ = C ]
= $${1 \over 2}$$ $$\varepsilon $$
0
B
2
$$ 	imes $$ $$\left( {{1 \over {{\varepsilon _0}{\mu _0}}}} ight)$$    [as   C
2
= $${{1 \over {{\varepsilon _0}{\mu _0}}}}$$]
=  $${{{B^2}} \over {2{\mu _0}}}$$
$$ 	herefore $$  U
B
= U
E

Answer

$${U_E} = {{{U_B}} \over 2}$$

Answer

$${U_E} > {U_B}$$

Answer

$${U_E} < {U_B}$$

Answer

$${U_E} = {U_B}$$

EM waves

The energy associated with electric field is (U E ) and with magnetic field is (U B ) for an electromagnetic wave in free space. Then :

Choose the correct answer: