A planar structure of length
L and width
W is made of two different optical media of refractive indices
n1=1.5 and
n2=1.44 as shown in figure. If
L≫W, a ray entering from end
AB will emerge from end
CD only if the total internal reflection condition is met inside the structure. For
L=9.6 m, if the incident angle
θ is varied, the maximum time taken by a ray to exit the plane
CD is
t×10−9 s, where
t is
[Speed of light
c=3×108 m/s ]