A double convex lens made of glass (refractive index n=1.5) has the radii of curvature of both the surfaces as 20cm. Incident light rays parallel to the axis of the lens will converge at a distance L such that

A double convex lens made of glass (refractive index n=1.5) has the ra

1.	A double convex lens made of glass (refractive index n=1.5) has the radii of curvature of both the surfaces as 20cm. Incident light rays parallel to the axis of the lens will converge at a distance L such that
Answer» `L=20cm` `L=10cm` `L=40cm` `L=20/3cm` Solution :(a) Here `n=1.5` as per sign convention followed `R_(1)=+20cm` and `R_(2)=-20cm` `:.1/f=(n-1)(1/(R_(1))-1/(R_(2)))=(1.3-1)[1/((+20))-1/((-20))]` `=0.5xx2/20=1/20impliesf=20cm` Incident rays travelling parallel to the axis of lens will converge at its SECOND principal focus. Hence `L=+20cm`.

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A double convex lens made of glass (refractive index n=1.5) has the radii of curvature of both the surfaces as 20cm. Incident light rays parallel to the axis of the lens will converge at a distance L such that

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