An object of size $7.5 \ cm$ is placed in front of a convex mirror of radius of curvature $25 \ cm$ at a distance of $40 \ cm$. The size of the image should be ........ $cm$.

When an object is placed at a distance of $25 \ cm$ from a concave mirror,the magnification is $m_1$. The object is moved $15 \ cm$ farther away with respect to the earlier position and the magnification becomes $m_2$. If $m_1/m_2 = 4$,the focal length of the mirror is $....... \ cm$ (Assume image is real and $m_1, m_2$ are numerical values).

$A$ concave mirror gives an image three times as large as the object placed at a distance of $20\,cm$ from it. For the image to be real,the focal length should be........$cm$

Consider a light source placed at a distance of $1.5 \ m$ along the axis facing the convex side of a spherical mirror of radius of curvature $1 \ m$. The position $(s^{\prime})$,nature and magnification $(m)$ of the image are

All of the following statements are correct except:

$A$ thin rod of length $f/3$ lies along the axis of a concave mirror of focal length $f$. One end of its magnified image touches an end of the rod. The length of the image is