1.

An observer can see through a pin-hole at the top end of a thin rid of height h, placed as shown in figure. The beaker height is 3h and its radius is h. When the beaker is filled with a liquid upto a height 2h, he can see the lower end of the rod. Find the refractive index of the liquid.

Answer»

SOLUTION :`PQ =QR =2h`
` therefore(2525)i=45^@`
`thereforeST =RT=h=KM=MN`
so` KS= sqrt(h^2 +(2h)^2)=hsqrt(5)`
` thereforesinr = (h)/(h sqrt(5))=(1)/(sqrt(5))`
` thereforemu = (sin i)/( sin r ) = ( sin 45^@ )/( 1//sqrt(5))=sqrt((5)/(2))`


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