Question 119: EM waves

Question

The electric field of a plane electromagnetic wave propagating along the x direction in vacuum is
$$\overrightarrow E  = {E_0}\widehat j\cos \left( {\omega t - kx} \right)$$.
 The magnetic field $$\overrightarrow B $$
, at the moment t = 0 is :

Accepted Answer

$$\overrightarrow E = {E_0}\,\cos (\omega t - kx)\widehat j$$
We know, $$E = BC$$
$$B_{0} = {E_{0} \over C} = {{{E_0}} \over {{1 \over {\sqrt {{\mu _0}{ \in _0}} }}}}$$
$$ \Rightarrow $$ $$B_{0} = {E_0}\sqrt {{\mu _0}{ \in _0}} $$
You can see direction of $$\overrightarrow B$$ is along z axis.
$$ 	herefore $$ $$\overrightarrow B = {E_0}\sqrt {{\mu _0}{ \in _0}} \cos (\omega t - kx)\widehat k$$
at t = 0
$$\overrightarrow B = {E_0}\sqrt {{\mu _0}{ \in _0}} \cos (kx)\widehat k$$

Answer

$$\overrightarrow B  = {{{E_0}} \over {\sqrt {{\mu _0}{ \in _0}} }}\cos \left( {kx} \right)\widehat j$$

Answer

$$\overrightarrow B  = {{{E_0}} \over {\sqrt {{\mu _0}{ \in _0}} }}\cos \left( {kx} \right)\widehat k$$

Answer

$$\overrightarrow B  = {E_0}\sqrt {{\mu _0}{ \in _0}} \cos \left( {kx} \right)\widehat k$$

Answer

$$\overrightarrow B  = {E_0}\sqrt {{\mu _0}{ \in _0}} \cos \left( {kx} \right)\widehat j$$

EM waves

The electric field of a plane electromagnetic wave propagating along the x direction in vacuum is $\overrightarrow E = {E_0}\widehat j\cos \left( {\omega t - kx} \right). The magnetic field \overrightarrow B $ , at the moment t = 0 is :

Choose the correct answer: