Suppose that the electric field part of an electromagnetic wave in vacuum is
`vecE=[(3.1 N.C^(-1)) "cos"{1.8 "rad" .m^(-1))y+(5.4xx10^6 "rad". s^(-1) ) t}]hati`
What is the direction of propagation?

Explanation

The given equation
`vecE=[3.1 cos (1.8 y + 5.4 xx 10^6 t)]hati`…(1)
may be compared with the standard equation of electric field
`vecE=[E_0 cos (ky + omegat)]hati` …(2)
and following conclusions drawn.
Along `-hatj` direction (`because` coefficient of y is positive )