Nature Of Electromagnetic Waves

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In a plane electromagnetic wave travelling through vacuum, how are the oscillating electric field, the oscillating magnetic field, and the direction of propagation oriented relative to one another?

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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} 	imes \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.

Nature Of Electromagnetic Waves

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