$A$ plano-convex lens of focal length $30\,cm$ has its plane surface silvered. An object is placed $40\,cm$ from the lens on the convex side. The distance of the image from the lens is.......$cm$

An upright object is placed at a distance of $40\, cm$ in front of a convergent lens of focal length $20\, cm$. $A$ convergent mirror of focal length $10\, cm$ is placed at a distance of $60\, cm$ on the other side of the lens. The position and size of the final image will be

$A$ thin convex lens of focal length $25 \, cm$ is cut into two pieces $0.5 \, cm$ above the principal axis. The top part is placed at $(0,0)$ and an object is placed at $(-50 \, cm, 0)$. Find the coordinates of the image.

$A$ concave mirror is placed on a horizontal table with its axis pointing vertically upwards. Let $O$ be the pole of the mirror and $C$ be its center of curvature. $A$ point object is placed at $C$. It forms a real image at $C$. If the mirror is now filled with water,the image will be formed . . . . . .

$A$ plano-convex lens $(f = 20 \ cm)$ is silvered at the plane surface. Now,the new focal length $F$ will be........$cm$.

The plane surface of a plano-convex lens of focal length $f$ is silvered. It will behave as