The figure shows a small concave mirror with $CP$ as its principal axis. $A$ ray $XY$ is incident on the mirror. Which of the four rays can be the reflected ray?

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 . . . . . $\text{cm s}^{-1}$.

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

$A$ short linear object $O$ is placed on the principal axis of a convex mirror of focal length $f$ as shown in the figure. The ratio of transverse magnification to longitudinal magnification is

$A$ concave mirror of radius of curvature $R$ has a circular outline of radius $r$. $A$ circular disc is to be placed normal to the axis at the focus,so that it collects all the light that is reflected from the mirror from a beam parallel to the axis. For $r \ll R$,the area of this disc has to be at least

$A$ student performed the experiment of determination of focal length of a concave mirror by $u-v$ method using an optical bench of length $1.5 \ m$. The focal length of the mirror used is $24 \ cm$. The maximum error in the location of the image can be $0.2 \ cm$. The $5$ sets of $(u, v)$ values recorded by the student (in $cm$) are: $(42, 56), (48, 48), (60, 40), (66, 33), (78, 39)$. The data set$(s)$ that cannot come from the experiment and is (are) incorrectly recorded,is (are):
$(A) (42, 56)$
$(B) (48, 48)$
$(C) (66, 33)$
$(D) (78, 39)$