An oil layer (Noil = 1.15) is spread smoothly and evenly over the surface of sea water (Nwater = 1.37), with a layer of air (Nair= 1) above the oil. A light ray is traveling upwards. What is the angle of refraction of the light ray as it enters the oil layer?
1) Cannot be determined without the incident angle
2) 30 degrees
3) 45 degrees
4) 60 degrees