Till what maximum distance. We can place the image which can be seen in the concave mirror

Q.

Upto what maximum distance from a concave mirror, the image can be obtained ? What will be the location of object for it ?

Q. An object of size (height) $7cm$ is placed at $25cm$ in front of concave mirror of focal length $15cm$. At what distance from the mirror should a screen be placed, so that we can get a sharp and clear image? Find nature and size (height) of the image.

Q. An object of size 7.0 cm is placed at 27 cm in front of concave mirror of for 18 cm. At what distance from the mirror should be placed, so that focused image can be obtained? Find the size and the nature of the image.

Q. Giving reasons, state the 'signs' (positive or negative) which can be given to the following:

(a) object distance (u) for a concave mirror or convex mirror
(b) image distance (v) for a concave mirror
(c) image distance (v) for a convex mirror

Q. An object of size 7.0 cm is placed at 27 cm in front of a concave mirror of focal length 18 cm. At what distance from the mirror should a screen be placed so that a sharp focussed image can be obtained? Find the size and nature of image.