A triangular medium has varying refracting index n = n0 + ax, where x is the distance (in cm) along x– axis from origin and n0 = 4/3 . A ray is incident normally on face OA at the mid–point of OA. The range of a so that light does not escape through face AB when it falls first time on the face AB (OA = 4 cm, OB = 3 cm and AB = 5 cm) : ( Surrounding medium is air)
(A) a > 1/9
(B) a > 2/9
(C) a > 1/3
(D) of these
