Question

In case of linearly polarised light, the magnitude of the electric field vector

• A. does not change with time
• B. varies periodically with time
• C. increases and decreases linearly with time
• D. is parallel to the direction of propagation

Answer 1

Answer: (B)

Light can be represented as a transverse electromagnetic wave made up of mutually perpendicular fluctuating electric and magnetic fields. The diagram shows the electric field in the $xy$-plane, the magnetic field in $xz$-plane and the propagation of the wave in the $x$-direction.

Fig. (2) shows a line tracing out the electric field vector as it propagates traditionally, only the electric field vector is dealt with because the magnetic field component is essentially the same.