Two mirrors $AB$ and $CD$ are arranged along two parallel lines. The maximum number of images of object $O$ that can be seen by any observer is

$A$ thick plane mirror shows a number of images of the filament of an electric bulb. Of these,the brightest image is the

If an observer is walking away from a plane mirror with a velocity of $6\;m/s$,then the velocity of the image with respect to the observer will be........$m/s$.

Two parallel mirrors $M_1$ and $M_2$ are separated by a distance $a$. An object is placed between them. What is the distance between the $n^{th}$ image formed by $M_1$ and the $n^{th}$ image formed by $M_2$?

$A$ girl of height $150 \,cm$ with her eye level at $140 \,cm$ stands in front of a plane mirror of height $75 \,cm$ fixed to a wall. The lower edge of the mirror is at a height of $85 \,cm$ above her feet level. The height of her image the girl can see in the mirror is (in $cm$)

An object is placed between two plane mirrors inclined at some angle to each other. If the number of images formed is $7$, then the angle of inclination is: (in $^{\circ}$)