For a convex lens,the distance of the object is taken on the $X$-axis and the distance of the image is taken on the $Y$-axis. The nature of the graph so obtained is:

If the focal lengths of a lens for red and violet light rays are $f_{R}$ and $f_{V}$ respectively,then which of the following is the true relationship?

There is an equiconvex glass lens with radius of each face as $R$,$_a{\mu _g} = 3/2$,and $_a{\mu _w} = 4/3$. If there is water in the object space and air in the image space,then the focal length is:

The radius of curvature of a convex lens is $40 \,cm$ for each surface. Its refractive index is $1.5$. Its focal length is: (in $\,cm$)

An object approaches a convergent lens from the left of the lens with a uniform speed $5 \, m/s$ and stops at the focus. The image:

$A$ point object is moving at a constant speed of $1 \,ms^{-1}$ along the principal axis of a convex lens of focal length $10 \,cm$. The speed of the image is also $1 \,ms^{-1}$, when the object is at what distance (in $cm$) from the optical centre of the lens?