An object is placed in front of a spherical concave mirror between the focal point $(F)$ and the center of curvature $(C)$. Its image is:

If an object is placed $10 \ cm$ in front of a concave mirror of focal length $20 \ cm,$ the image will be

$A$ straight line joining the object point and image point is always perpendicular to the mirror:

In the case of spherical mirrors,the images formed on the side of the object and images formed on the opposite side are respectively

$A$ concave mirror of focal length $f$ forms an image $n$ times the size of the object. If the image is real, then the distance of the object from the mirror is .......

An object and a concave mirror of focal length $f=10 \text{ cm}$ both move along the principal axis of the mirror with constant speeds. The object moves with speed $V_0=15 \text{ cm s}^{-1}$ towards the mirror with respect to a laboratory frame. The distance between the object and the mirror at a given moment is denoted by $u$. When $u=30 \text{ cm}$,the speed of the mirror $V_m$ is such that the image is instantaneously at rest with respect to the laboratory frame,and the object forms a real image. The magnitude of $V_m$ is . . . . . $\text{cm s}^{-1}$.