A vertical beam of light of cross sectional radius `(R)/(2)` is incident symmetrically on the curved surface of a glass hemisphere of refractive index `mu = (3)/(2)`. Radius of the hemisphere is R and its base is on a horizontal table. Find the radius of luminous spot formed on the table. `sin 20^(@) = (1)/(3)` and `sin 80^(@) = 0.98`
