Thu September 06, 2012 By: Pramesha Biswas

Suppose that electric feild part of an EM wave in vacuum is E(y)=0.5cos[2(pi)X10(power 8)(t-(x/c})], E(x)=0 and E9z)=0. All quantities have SI unit (i)What is the direction of propagation? (ii)What is the frequency? (iii) What is the amplitude of the magnetic feild part of the wave? Write the equation of associated magnetic feild.

Expert Reply
Wed September 12, 2012
Since the variation is along the y direction only and the variation in y direction is with x direction thus the direction odf wave propagation is positive x direction.
the general wave equation is:
E(y) = Eo Cos( wt -kx)
thus according to it the frequancy is 2(pi)x108
and the amplitude of electric field is 0.5
thus the amplitude of magnetic field will be = Bo = cEo
and the frequency of the wave will be same and the direction of propagation will remain same just the variation will be in z direction
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