While capturing solar energy for commercial purposes,we use:

$A$ convex mirror of focal length $f$ is placed at the origin with its reflecting surface towards the negative $x-$ axis. Choose the correct graph between $v$ and $u$ for $u < 0$.

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

$A$ candle flame of $3 \, cm$ is placed at $300 \, cm$ from a wall. $A$ concave mirror is kept at distance $x$ from the wall in such a way that the image of the flame on the wall is $9 \, cm$. Then $x$ is......$cm$.

When an object is placed $40\ cm$ away from a spherical mirror,an image of magnification $\frac{1}{2}$ is produced. To obtain an image with magnification of $\frac{1}{3}$,the object is to be moved $:$

$A$ virtual image larger than the object can be obtained by