Question

An e.m. wave trevels in vacuum along z direction:
`vecE=(E_1hati+E_2hatj)cos (kz-omegat)`. Choose the correct option from the following :
A. The associated magnetic field is given as `vecB=1/c(E_1hati+E_2hatj) cos (kz-omegat)`
B. The associated magnetic field is given as `vecB=1/c(E_1hati-E_2hatj) cos (kz-omega)`
C. The given electromagnetic field circular polarised
D. The given e.m. wave is plane polarised

Answer 1

Correct Answer - (a,d)
In em wave, the electric field vector is given as, `vecE=(E_1hati+E_2hatj)cos (kz-omegat)`
In em wave, the associated magnetic field vector, `vecB=(vecE)/c=(E_1hati+E_2hatj)/c cos (kz-omegat)`
Thus, option (a) is correct. As `vecE and vecB` are perpendicular to each other and the propagation of em
wave is `botr` to `vecE` as well as `vecB`, so the given em wave is plane polarised. Thus option (d) is true.