An initially parallel cylindrical beam travels in a medium of refracti

1.	An initially parallel cylindrical beam travels in a medium of refractive index, µ(I) = µ0 + µ2I, where µ0 and µ2are positive constants and I is intensity of light beam. The intensity of the beam is decreasing with increasing radius. (i). As the beam enters the medium, it will : (a) Converge (b) Diverge near the axis and converge near the periphery.(c) Travel as a cylindrical beam (d) Diverge. (ii). The speed of light in the medium is : (a) The same everywhere in the beam (b) Directly proportional to the intensity I (c) Maximum on the axis of the beam (d) Minimum on the axis of the beam.(iii). The initial shape of the wave-front of the beam is: (a) Concave (b) Convex near the axis and concave near the periphery (c) Planar (d) Convex
Answer» (1). Option : (a) As the medium is denser W.R.T. vacuum, therefore, on entering the medium, it will converge. (2). Option : (d) The speed of light in the medium is minimum on the axis of the beam, because refractive index of medium is maximum at the axis of the beam. (3). Option : (c) The initial shape of the wavefront of the beam is planar, as the wave-front lies in the plane of the beam.

An initially parallel cylindrical beam travels in a medium of refractive index, µ(I) = µ0 + µ2I, where µ0 and µ2are positive constants and I is intensity of light beam. The intensity of the beam is decreasing with increasing radius. (i). As the beam enters the medium, it will : (a) Converge (b) Diverge near the axis and converge near the periphery.(c) Travel as a cylindrical beam (d) Diverge. (ii). The speed of light in the medium is : (a) The same everywhere in the beam (b) Directly proportional to the intensity I (c) Maximum on the axis of the beam (d) Minimum on the axis of the beam.(iii). The initial shape of the wave-front of the beam is: (a) Concave (b) Convex near the axis and concave near the periphery (c) Planar (d) Convex

Answer»

(1). Option : (a)

As the medium is denser W.R.T. vacuum, therefore, on entering the medium, it will converge.

(2). Option : (d)

The speed of light in the medium is minimum on the axis of the beam, because refractive index of medium is maximum at the axis of the beam.

(3). Option : (c)

The initial shape of the wavefront of the beam is planar, as the wave-front lies in the plane of the beam.