question_answer

A plane electromagnetic wave travels in vacuum along\[\hat{k}\]direction, where\[\hat{i},\hat{j}\]and\[\hat{k}\]are unit vectors along the\[x,\text{ }y\]and z directions and z directions. The direction along which the electric and the magnetic field vectors point may be respectively:

A)  \[\hat{i}\,and\,\hat{j}\]                              

B)  \[\hat{i}\,and\,-\hat{j}\]            

C)         \[\hat{j}\,\,and\,\hat{i}\]           

D)         \[\hat{k}\,\,and\,\hat{i}\]

E)  \[\hat{k}\,\,and\,\hat{j}\]

Correct Answer: A

Solution :

In electromagnetic waves, the electric field E and magnetic field B are perpendicular to each other and also perpendicular to the direction of propagation of the wave. Hence, direction of electric field and magnetic field vectors point in the \[\hat{i}\,and\,\hat{j}\] direction.