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(B) The direction of propagation of an electromagnetic wave is given by the direction of the Poynting vector,which is $\vec{E} 	imes \vec{B}$.Given t

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$-\hat{j}+\hat{k}, -\hat{j}-\hat{k}$

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(B) The direction of propagation of an electromagnetic wave is given by the direction of the Poynting vector,which is $\vec{E} 	imes \vec{B}$.Given the wave propagates in the $x$-direction,we must have $\vec{E} 	imes \vec{B} = \hat{i}$.Let us check option $B$: $\vec{E} = -\hat{j} + \hat{k}$ and $\vec{B} = -\hat{j} - \hat{k}$.Calculating the cross product: $(-\hat{j} + \hat{k}) 	imes (-\hat{j} - \hat{k}) = (-\hat{j} 	imes -\hat{j}) - (\hat{j} 	imes -\hat{k}) + (\hat{k} 	imes -\hat{j}) - (\hat{k} 	imes -\hat{k})$.$= 0 + (\hat{j} 	imes \hat{k}) - (\hat{k} 	imes \hat{j}) - 0 = \hat{i} - (-\hat{i}) = 2\hat{i}$.Since the resulting vector is in the $x$-direction,option $B$ is correct.

For a plane electromagnetic wave propagating in the $x$-direction,which one of the following combinations gives the correct possible directions for the electric field $(E)$ and magnetic field $(B)$ respectively?

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