A piano-convex lens -refractive index mu-1- fits exactly into a piano-concave lens -refractive index mu-2- Their plane surfaces are parallel to each other- R is the radius of curvature of the curved surface of the lenses- then focal length of the combination is-displaystyle frac-R-mu-1 - mu-2-displaystyle frac-2R-mu-2 - mu-1-displaystyle frac-R-2-mu-1 - mu-2-none of these

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Toppr Admin · Accepted Answer

1r-x3BC-1-x2212-1R-1-x2212-x3BC-2-x2212-R-x3BC-1-x3BC-2-x2212-2Rf-R-x3BC-1-x3BC-2-x2212-2- Hence none of them -xA0-are correct-xA0-xA0-

1r=μ1−1R+1−μ2−R=(μ1+μ2)−2Rf=R(μ1+μ2)−2, Hence none of them are correct

$\frac{1}{r} = \frac{μ_{1} - 1}{R} + \frac{1 - μ_{2}}{- R} = \frac{(μ_{1} + μ_{2}) - 2}{R}$

$f = \frac{R}{(μ_{1} + μ_{2}) - 2}$ , Hence none of them are correct