In what direction does an electromagnetic wave travel?
It depends on the phase angle of the magnetic field
It travels parallel to the electric and magnetic fields
It depends on the phase angle of the electric field
It travels at a right angle to the electric and magnetic fields✓الإجابة الصحيحة
الشرح
In a plane electromagnetic wave the direction of energy flow is given by the cross product of the electric and magnetic field vectors, so it is perpendicular to both. Travel parallel to the fields would make the wave longitudinal, which free-space electromagnetic waves are not, and the phase angle of either field does not determine the direction of travel.