[" An em wave is propagating in a medium with a "],[" velocity "vec V=Vi" .The instantaneous oscillating "],[" electric field of this em wave is along + y axis.Then "],[" the direction of this em wave is along + y axis.Then "],[" wave will be along :- "],[" (1) - direction "],[" (2) + a direction "],[" (3) - y direction "],[" (4) - x direction "]