### Theory:

Let us now find the position, size and nature of the image by drawing the ray diagram for a small linear object placed on the principal axis of a concave mirror at different positions.

Case-I: When the object is placed at infinity, the rays of light reaching the concave mirror is parallel to each other.
Position of the Image: The image is formed at the principal focus $$F$$.
Nature of the Image: Real, inverted and highly diminished in size.

Case-II: When the object is placed beyond the centre of curvature.

Position of the image: Between the principal focus $$F$$ and centre of curvature $$C$$.
Nature of the image: Real, inverted and smaller than an object.

Case-III: When the object is placed exactly at the centre of curvature.

Position of the image: The image is at the centre of curvature itself.
Nature of the image: Real, inverted, and same size as the object.

Case-IV: When the object is placed between the centre of curvature $$C$$ and principal focus $$F$$.

Position of the image: The image is beyond $$C$$.
Nature of the image: Real, inverted and magnified.

Case-V: When the object is placed at the principal focus $$F$$.

Position of the image: The image is beyond at infinity.
Nature of the image: Real, inverted and magnified.

Case-VI: When the object is placed between the focus $$F$$ and the pole $$P$$.

Position of the image: The image is behind the mirror.
Nature of the image: Virtual, erect and magnified.