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(D) The direction of propagation of an electromagnetic wave is given by the direction of the Poynting vector,which is parallel to $\vec{E} 	imes \vec

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$-z$-direction

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(D) The direction of propagation of an electromagnetic wave is given by the direction of the Poynting vector,which is parallel to $\vec{E} 	imes \vec{B}$.Given the direction of the magnetic field is $\hat{B} = \hat{i} - \hat{j}$.Given the direction of the electric field is $\hat{E} = \hat{i} + \hat{j}$.The direction of propagation $\hat{n}$ is given by the cross product of the unit vectors of the electric and magnetic fields:$\hat{n} = \hat{E} 	imes \hat{B} = (\hat{i} + \hat{j}) 	imes (\hat{i} - \hat{j})$.Expanding the cross product:$\hat{n} = (\hat{i} 	imes \hat{i}) - (\hat{i} 	imes \hat{j}) + (\hat{j} 	imes \hat{i}) - (\hat{j} 	imes \hat{j})$.Using the properties of unit vectors $\hat{i} 	imes \hat{i} = 0$,$\hat{j} 	imes \hat{j} = 0$,$\hat{i} 	imes \hat{j} = \hat{k}$,and $\hat{j} 	imes \hat{i} = -\hat{k}$:$\hat{n} = 0 - \hat{k} - \hat{k} - 0 = -2\hat{k}$.Since the direction is $-2\hat{k}$,the wave is travelling along the $-z$-direction.

At an instant,a plane electromagnetic wave has its magnetic field in the direction of the vector $\hat{i}-\hat{j}$ and its electric field is in the direction of $\hat{i}+\hat{j}$. The wave is travelling along which direction?

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