At what distance in front of a concave mirror of focal length $30\; cm$,should an object be placed (in $cm$) so that its real image of size three times that of the object is obtained?

Suppose that the lower half of the concave mirror's reflecting surface in the figure is covered with an opaque (non-reflective) material. What effect will this have on the image of an object placed in front of the mirror?

The cross-section of a reflecting surface is represented by the equation $x^{2}+y^{2}=R^{2}$ as shown in the figure. $A$ ray travelling in the positive $x$ direction is directed toward the positive $y$ direction after reflection from the surface at point $M$. The coordinate of the point $M$ on the reflecting surface is

The image formed by a convex mirror of focal length $f$ is $(1/n)$ times the size of the object. The distance of the object from the mirror is:

$A$ concave mirror of focal length $10$ cm forms an image which is double the size of the object when the object is placed at two different positions. The distance between the two positions of the object is . . . . . . cm.

$A$ mobile phone lies along the principal axis of a concave mirror,as shown in the figure. Show by a suitable diagram,the formation of its image. Explain why the magnification is not uniform. Will the distortion of the image depend on the location of the phone with respect to the mirror?