A plane electromagnetic wave travelling along +z-direction,

A plane electromagnetic wave travelling along +z-direction, has its electric field given by E_x = 2 cos (t) and E_y = 2 cos (t + 90) the wave is—

1. Linearly polarised
2. Right circularly polarised
3. Left circularly polarised
4. Elliptically polarised

E_x = 2 cos ωt,
E_y = 2 cos (ωt + 90º)
= – 2 sin ωt
E_y/ E_x = – tan ωt
This is a left circularly polarized wave.