Question

In which direction do the electric and magnetic field vector oscillate in an electromagnetic wave propagating

Answer 1

Electromagnetic (EM) waves are changing electric and magnetic fields, transporting energy and momentum through space.  EM waves are solutions of Maxwell's equations, which are the fundamental equations of electrodynamics.  EM waves require no medium, they can travel through empty space.  Sinusoidal plane waves are one type of electromagnetic waves.  Not all EM waves are sinusoidal plane waves, but all electromagnetic waves can be viewed as a linear superposition of sinusoidal plane waves traveling in arbitrary directions.  A plane EM wave traveling in the x-direction is of the form

E(x,t) = Emaxcos(kx - ωt + φ), B(x,t) = Bmaxcos(kx - ωt + φ).

E is the electric field vector, and B is the magnetic field vector of the EM wave.  For electromagnetic waves Eand B are always perpendicular to each other and perpendicular to the direction of propagation.  The direction of propagation is the direction of E x B.

Let the fingers of your right hand point in the direction of E.  Orient the palm of your hand so that, as you curl your fingers, you can sweep them over to point in the direction of B.  Your thumb points in the direction of E x B.

Let i denote the x-direction, jthe y-direction and k the z-direction.  If for a wave traveling in the x-direction E = E j, then B = B k and j x k = i.  Electromagnetic waves are transverse waves.

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Answer 2

Answer:

The cross product of electric and magnetic field vectors i.e. E → × B → gives the direction in which the wave travels. It is given that wave is propagating along the x-axis. This means that electric field vector is oscillating in positive y-direction and magnetic field vector in positive z-direction.