(A) According to the Lens Maker's Formula,the focal length $f'$ of a lens in a medium is given by $\frac{1}{f'} = (\frac{n_{1}}{n_{2}} - 1)(\frac{1}{R

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Either as a convex or as a concave lens depending solely on $R$

(A) According to the Lens Maker's Formula,the focal length $f'$ of a lens in a medium is given by $\frac{1}{f'} = (\frac{n_{1}}{n_{2}} - 1)(\frac{1}{R_{1}} - \frac{1}{R_{2}})$.For a biconvex lens,$R_{1} = R$ and $R_{2} = -R$,so $(\frac{1}{R_{1}} - \frac{1}{R_{2}}) = \frac{2}{R}$.Thus,$\frac{1}{f'} = (\frac{n_{1}}{n_{2}} - 1)(\frac{2}{R})$.If $n_{1} > n_{2}$,then $(\frac{n_{1}}{n_{2}} - 1) > 0$,so $f' > 0$,and the lens behaves as a convex (converging) lens.If $n_{1} Therefore,the behavior of the lens depends on the relative values of $n_{1}$ and $n_{2}$.

Class 12 Physics Ray Optics and Optical Instruments Refraction by Lenses

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$A$ biconvex lens of focal length $f$ and radii of curvature of both surfaces $R$ is made of a material of refractive index $n_{1}$. This lens is placed in a liquid of refractive index $n_{2}$. How will this lens behave?

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A
Either as a convex or as a concave lens depending solely on $R$
B
$A$ convex lens depending on $n_{1}$ and $n_{2}$
C
$A$ concave lens depending on $n_{1}$ and $n_{2}$
D
$A$ convex lens of same focal length irrespective of $R, n_{1}$ and $n_{2}$

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$A$ biconvex lens of focal length $f$ and radii of curvature of both surfaces $R$ is made of a material of refractive index $n_{1}$. This lens is placed in a liquid of refractive index $n_{2}$. How will this lens behave?

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The radius of curvature of each surface of a convex lens having refractive index $1.8$ is $20 \ cm$. The lens is now immersed in a liquid of refractive index $1.5$. The ratio of power of the lens in air to its power in the liquid will be $x : 1$. The value of $x$ is $.....$

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