A Tank Contains A Slab Of Glass 8 Cm Thick And Of Refractive Index 1.6. Above This Is A Depth Of 4.5 Cm Of An Oil And Upon This Floats A Layer Of Water 6 Cm Thick And Of Refractive Index 4/3. To An Observer Looking Down From Above, A Mark At The Bottom Of The Glass Slab Appears To Be Raised Up To Position 6 Cm From The Bottom Of The Slab. The Refractive Index Of Oil Is

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A tank contains a slab of glass 8 cm thick and of refractive index 1.6. Above this is a depth of 4.5 cm of an oil and upon this floats a layer of water 6 cm thick and of refractive index 4/3. To an observer looking down from above, a mark at the bottom of the glass slab appears to be raised up to position 6 cm from the bottom of the slab. The refractive index of oil is


Correct option is



O is the mark at the bottom of the glass slab (fig.). Since the boundaries of the media are parallel, the total shift of the mark O is equal to the shift due to each of the three media. Let  be the refractive index of the oil.   

Total apparent shift (OI) = shift due to glass + shift due to oil + shift due to water




But                  OI = 6 cm (given). Hence   





Monochromatic light is refracted from air into glass of refractive index μ. The ratio of the wavelengths of the incident and refracted waves is


The layered lens shown in fig. is made of two kinds of glass. A point source of light is placed on its principal axis. If reflections from the boundaries between layers are ignored, the lens will form



How much time will light take to transverse a glass slab of thickness 10 cm and refractive index 1.5?


A glass prism ABC of refractive index 1.5 is immersed in water of refractive index 4/3 as shown in fig. A ray of light incident normally on face AB is totally reflected at face AC if  



What is the relation between refractive indices μμ1 and μ2 if the behavior of light rays is as shown in fig.



A lens forms a sharp image on a screen. On inserting a parallel sided glass slab between the lens and the screen, it is found necessary to move the screen a distance d away from the lens is order to focus the image sharply. If the refractive index of glass relative to air is μ, the thickness of the glass slab is given by


A convex lens is placed between an object and a screen which are a fixed distance apart. For one position of the lens the magnification of the image obtained on the screen is m1. When the lens is moved by a distance d, the magnification of the image obtained on the same screen is m2. The focal length of the lens is (m1 > m2).      


A vessel of depth t is half filled with oil of refractive index  and the other half is filled with water of refractive index . The apparent depth of the vessel when viewed from above is     


A ray of light, travelling in a medium of refractive index μ, is incident at an angle i on a composite transparent plate consisting of three plates of refractive indices . The ray emerges from the composite plate into a medium of refractive index , at angle x. Then  


The principle section of a glass prism is an isosceles triangle ABC with ABAC. The face AC is silvered. A ray incident normally on face AB, after two reflections, emerges from the base BC in a direction perpendicular to it. What is the BAC of the prism?