If the lateral magnification is $-2$ for a virtual object in a spherical mirror,then:

$A$ 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 ...... $cm$.

An object is placed at a distance of $40 \, cm$ from a concave mirror of focal length $15 \, cm$. If the object is displaced through a distance of $20 \, cm$ towards the mirror,the displacement of the image will be:

Let the transverse magnification produced by a spherical mirror be $m$. Then,for the same position of the object,the longitudinal magnification will be:

$A$ square of side $3 \ cm$ is placed at a distance of $25 \ cm$ from a concave mirror of focal length $10 \ cm$. The center of the square is on the axis of the mirror and the plane is perpendicular to the axis. The area enclosed by the image of the square is ........ $cm^2$.

An object is placed $40\;cm$ from a concave mirror of focal length $20\;cm.$ The image formed is