Nature Of Electromagnetic Waves

An electromagnetic wave is transverse, meaning the field oscillations occur at right angles to the direction in which energy travels. Maxwell's equations require that the electric field \vec{E}, the magnetic field \vec{B}, and the propagation direction form a right-handed mutually perpendicular set, with \vec{E} \times \vec{B} pointing along the direction of travel. The two fields oscillate in phase, reaching their maxima and zeros together, and their magnitudes are linked by E = cB. Saying the electric field is parallel to the magnetic field contradicts the cross-product structure that defines wave propagation. Claiming both fields point along the propagation direction would make the wave longitudinal, which electromagnetic waves are not. The final option is self-contradictory because perpendicular fields cannot both lie along a single propagation axis. This transverse, mutually perpendicular geometry is the defining picture presented in the NCERT Electromagnetic Waves chapter and underlies polarization. A simple consistency check: only mutually perpendicular \vec{E} and \vec{B} give a non-zero, steady Poynting vector along the travel direction, which is exactly what carries the wave's energy forward.