$A$ concave mirror of focal length $10$ cm forms an image which is double the size of the object when the object is placed at two different positions. The distance between the two positions of the object is . . . . . . cm.

$A$ person looks at the image of two parallel finite length lines $PQ$ and $RS$ in a convex mirror (see figure). Which of the following represents schematically the image correctly? Note: Letters $P, Q, R$ and $S$ are used only to denote the endpoints of the lines.

An object is placed in front of a concave mirror of focal length $f$. $A$ virtual image is formed with a magnification of $2$. To obtain a real image of the same magnification,the object has to be moved by a distance of:

$A$ straight metal rod of length $6 \ cm$ is placed along the principal axis of a concave mirror of focal length $9 \ cm$ such that the end of the rod closer to the mirror is at a distance of $15 \ cm$ from the pole of the mirror. The length of the image of the rod is (in $cm$)

$A$ small rod of length $2 \, mm$ lies along the principal axis at a distance of $30 \, cm$ from a concave mirror of focal length $20 \, cm$. The axial length of the image of the rod is.....$mm$.

An object is placed in front of a spherical mirror, and a $2$ times magnified image is formed on a screen. Choose the $\text{CORRECT}$ option.