If the image of an object is at the focal point $f$ to the right side of a convex lens, the position of the object on the left of the lens is at

$A$ film projector magnifies a film onto a screen of area $100 \, cm^2$. If the linear magnification is $4$,what will be the area of the image on the screen in $cm^2$?

If ${I_1}$ and ${I_2}$ are the sizes of the images for the two positions of the lens in the displacement method,then the size of the object is given by:

$A$ beam of light converges at a point $P$. Now a lens is placed in the path of the convergent beam $12 \, cm$ from $P$. At what point does the beam converge if the lens is a concave lens of focal length $16 \, cm$ (in $, cm$)?

$A$ convex lens of focal length $20 \ cm$ produces images of the same magnification $2$ when an object is kept at two distances $x_1$ and $x_2$ $(x_1 > x_2)$ from the lens. The ratio of $x_1$ and $x_2$ is

You are given two lenses,a converging lens with focal length $+10\, cm$ and a diverging lens with focal length $-20\, cm$. Which of the following would produce a virtual image that is larger than the object?