The focal length of a plano-convex lens is equal to its radius of curvature. Find the refractive index of its material.

$A$ double convex lens of glass of $\mu = 1.5$ has a radius of curvature of each of its surfaces equal to $0.2 \ m$. The power of the lens is:

$A$ point object in air is in front of the curved surface of a plano-convex lens. The radius of curvature of the curved surface is $30 \; cm$ and the refractive index of the lens material is $1.5$. Then the focal length of the lens (in $cm$) is:

$A$ convex lens has power $P$. It is cut into two halves along its principal axis. Further,one piece (out of the two halves) is cut into two halves perpendicular to the principal axis (as shown in the figure). Choose the incorrect option for the reported pieces.

The unit of focal power of a lens is

$A$ thin convex lens made from crown glass $\left( \mu = \frac{3}{2} \right)$ has focal length $f$. When it is measured in two different liquids having refractive indices $\frac{4}{3}$ and $\frac{5}{3}$,it has the focal lengths $f_1$ and $f_2$ respectively. The correct relation between the focal lengths is: