Which of the following diagrams represent the veriation of electric field vector with time for a circularly polarised light

Options

A.
B.
C.
D.

Answer

B

Explanation

When two plane-polarised waves are superimposed then under certain conditions, the resultant light vector rotates with a constant magnitude in a plane perpendicular to the direction of propagation. The tip of the vector traces a circle and the light is said to be circularly polarised.
To form circularly polarised light,
`E_(x)=E_(0)sinomegat`
`E_(y)=E_(0)cosomegat=E_(0)sin(omegat+pi/2)`
where, `E_(0)` is amplitude.
Resultant amplitude,
`|E|^(2)=E_(0)+E_(0)+2E_(0)*E_(0)cos""pi/2`
`|E|^(2)=2E_(0)="constant"`