$A$ concave mirror for face viewing has a focal length of $0.4\,m$. The distance at which you hold the mirror from your face in order to see your image upright with a magnification of $5$ is......$m$.

An object of height $3.6 \ cm$ is placed normally on the principal axis of a concave mirror of radius of curvature $30 \ cm$. If the object is at a distance of $10 \ cm$ from the principal focus of the mirror, then the height of the real image formed due to the mirror is (in $cm$)

In a concave mirror experiment,an object is placed at a distance ${x_1}$ from the focus and the image is formed at a distance ${x_2}$ from the focus. The focal length of the mirror would be

$A$ virtual image three times the size of the object is obtained with a concave mirror of radius of curvature $36 \ cm$. The distance of the object from the mirror is ........ $cm$.

$A$ square cardboard of side $3\, cm$ is placed $25\, cm$ from a concave mirror of focal length $10\, cm$. What is the area enclosed by the image of the cardboard? (The plane of the cardboard is perpendicular to the principal axis.)

$A$ diminished virtual image can be formed only in