We know that if the object is place between focus and pole in front of concave mirror then the image formed by concave mirror is virtual, erect and larger the size of object. So in this question focus length is 12cm.Then (a)If we put the object between 0 to 12cm in front of concave mirror then we find erect image.
(b) The image is larger than the object.
For image formation in concave mirrer in above case
a ray parallel to principle axis after reflection passes through focus and ray trough centre of carveture retrace the path if the ray are produce back they appear to come from a point which is behind the mirror that place the image is formed.

Answer:

Concave Mirror and Formation of Image:

A concave mirror is a spherical mirror in which the reflecting surface is bent inwards. The reflecting surface of the mirror is known as the concave surface. When an object is placed in front of a concave mirror, the light rays emanating from the object get reflected by the mirror and converge at a point. This point is known as the focus of the mirror. The distance between the focus and the reflecting surface of the mirror is known as the focal length of the mirror.

When the object is placed beyond the focus of the mirror, the image formed is real, inverted, and diminished in size. When the object is placed between the focus and the reflecting surface of the mirror, the image formed is virtual, erect, and magnified in size.

Range of Distance of Object Placed in Front of the Mirror:

In order to obtain an erect image of an object using a concave mirror of focal length 12 cm, the object should be placed between the focus and the reflecting surface of the mirror. The range of distance of the object placed in front of the mirror can be calculated using the mirror formula, which is given by:

1/v + 1/u = 1/f

where v is the distance of the image from the mirror, u is the distance of the object from the mirror, and f is the focal length of the mirror.

Since we want to obtain an erect image, the image distance v will be positive. The focal length of the mirror is given as 12 cm. Therefore, we can rearrange the mirror formula to obtain the range of distance of the object as:

12/13 cm ≤ u ≤ ∞

This means that the object should be placed between 12/13 cm and infinity from the mirror.

Size of Image:

When an object is placed between the focus and the reflecting surface of a concave mirror, the image formed is virtual, erect, and magnified in size. Therefore, the image formed in this case will be larger than the object.

Ray Diagram:

A ray diagram is a diagram that shows the path of light rays as they pass through an optical system. In the case of a concave mirror, a ray diagram can be drawn to show the formation of the image. The following steps can be followed to draw a ray diagram:

1. Draw a ray parallel to the principal axis of the mirror. This ray will pass through the focus after reflection.

2. Draw a ray passing through the focus of the mirror. This ray will become parallel to the principal axis after reflection.

3. Draw a ray passing through the center of curvature of the mirror. This ray will be reflected back along the same path.

4. The point where the three rays intersect will be the position of the image.

Therefore, the ray diagram for the formation of an erect image using a concave mirror of focal length 12 cm is as follows:


In this diagram, AB is the object, F is the focus of the mirror, C is the center of curvature of the mirror, A'B' is the image formed, and P and Q are the points of incidence and reflection of the rays. The image formed is virtual, erect