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A concave mirror of radius of curvature two meter is placed at the bottom of the tank of water. The mirror forms an image of the sun when it is directly overhead. Calculate the images from the mirror for (i) 160 cm and (ii) 80 cm of water in the tank. (Take,µ=4/3 for water) |
Answer» Solution :(i)  Focal lengh of mirror, `f=R/2=200/2=100 cm` For PARALLEL rays, image is formed at focus of mirror, PI=100 cm (II) When DEPTH of water is 80 cm  `musini=1xxsinr` As angles i and r are small, sin i= tan i, SINR =tanr `4/3cdot(AB)/(OB)=(AB)/(BI)rArr4/3cdot1/20=1/(BI)` `BI=15cmrArrPI=80+BI=80+15=95 cm` Alternatively `MU(BI)=BOrArr4/3xxBI=20rArrBI=15cm` |
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