A point source of light S is placed at the bottom of a vessel containg a liquid of refractive index 5//3. A person is viewing the source from above the surface. There is an opaque disc of radius 1 cm floating on the surface. The centre of the disc lies vertically above the source S. The liquid from the vessel is gradually drained out through a tap. What is the maximum height of the liquid for which the source cannot at all be seen from above?

A point source of light S is placed at the bottom of a vessel containg

1.	A point source of light S is placed at the bottom of a vessel containg a liquid of refractive index 5//3. A person is viewing the source from above the surface. There is an opaque disc of radius 1 cm floating on the surface. The centre of the disc lies vertically above the source S. The liquid from the vessel is gradually drained out through a tap. What is the maximum height of the liquid for which the source cannot at all be seen from above?
Answer» Solution :SEE the RESULT of sample EXAMPLE `R=h/(SQRT(u^2-1))` `h=Rsqrt(u^2-1)` `=(1 cm)sqrt((5//3)^2-1)=4/3 cm`

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