How to draw image formation by concave mirror

We must understand the rules of reflection of specific rays by a spherical mirror.

We should follow the following steps in drawing image formation.

These steps can be used in drawing image formation by convex mirror also.

1. Draw a concave mirror with its principal axis.

2. Now mark the Focus point (F) and center of curvature(C) on the principal axis. The center of curvature is double of focal length(f).

3. Now we place the object on the principal axis at the given positions. The object is an up-arrow (↑).

4. Now draw two lines from the tip (point A) of the arrow.

5. Now follow the rules of reflection of specific rays by a spherical mirror. The first ray is parallel to the principal axis and after reflection, it goes through the focus point( F).

6. The second ray incident on the mirror after passing through C or F or on the P(pole). Follow the rules of reflection for these positions.

7. Now find where both reflected rays intersect. At this position, an image is formed.

8. If reflected rays intersect, the image is real and inverted.

9. If reflected rays do not intersect, then we can extend the rays backward. The image formed is virtual and erect.

10. Now we determine the size of the image by observing its position in relation to the object. 

    u =  object distance

v =  image distance

          u > v  =  image is smaller than the object

          u< v   =  image is larger than the object 

          u =v =  image is the same size as that of object

These are the basic steps in drawing image formation by concave mirror and convex mirror. For image formation, we should follow the rules of the ray diagram.

Related Topics

1. Object beyond C

2. Object at C

3. Object at infinity

4. Object between C and F

5. 

Image formation by convex mirror

1. Object between infinity and mirror

2. Object at infinity