Total Internal Reflection: a Tank Holds a 1

Multiple Choice

Total internal reflection: A tank holds a 1.44-m thick layer of oil that floats on a 0.96-m thick layer of brine. Both liquids are clear and do not intermix. Point O is at the bottom of the tank, on a vertical axis. The indices of refraction of the oil and the brine are 1.40 and 1.52, respectively. A ray originating at O reaches the brine-oil interface at the critical angle. What is the distance of this point from the axis?

A) 1.5 m
B) 1.7 m
C) 1.9 m
D) 2.1 m
E) 2.3 m