A vessel contains a slab of glass
8 cm thick and of refractive index
1.6. Over the slab, the vessel is filled by oil of refractive index
μ upto height
4.5 cm and also by another liquid i.e., water of refractive index
43 and height
6 cm. As shown in figure. As observer looking down from above, he observes that, a mark at the bottom of the glass slab appears to be raised up to position
6 cm from the bottom of the slab. Refractive index (
μ) of oil is: