CBSE Class 12 · 2017 · EM WavesShort Answer

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How is an electromagnetic wave produced? Draw a sketch of a plane electromagnetic wave propagating along the X-axis, depicting the directions of the oscillating electric and magnetic fields.

Answer: By an accelerating/oscillating charge. Sketch: $E$ oscillating along y, $B$ along z, propagation along x.

Solution

An electromagnetic wave is produced by an accelerating or oscillating electric charge, which radiates coupled time-varying electric and magnetic fields.
For propagation along x, the sketch shows the electric field oscillating in the x--y plane,

E_{y} = E_{0} sin (k x - ω t)

, and the magnetic field oscillating in the x--z plane,

B_{z} = B_{0} sin (k x - ω t)

, in phase and mutually perpendicular.

E ∥ y, B ∥ z, propagation along x

CBSE Class 12 Board · 2017 · Subjective

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