Formation of image by a concave mirror

Formation of Image by a Concave Mirror

Introduction:
A concave mirror is a type of spherical mirror that has an inwardly curved reflecting surface. It is known as a converging mirror because it reflects incoming parallel light rays toward a common point called the focus. Concave mirrors are frequently utilized in items such as flashlights, shaving mirrors, and satellite receivers.

Key Terms to Know:

• Pole (P): The central point on the surface of the mirror.
• Center of Curvature (C): The center of the sphere from which the mirror is taken.
• Principal Axis: A straight line passing through the pole and center of curvature.
• Focus (F): The point where light rays parallel to the principal axis meet after reflection.
• Focal Length (f): The length separating the pole and the focus point.

Image Formation in Different Object Positions:
The image formed by a concave mirror changes depending on the distance of the object from the mirror. These changes can be understood using ray diagrams.

1. Object at Infinity:
When the object is far away, rays are parallel to the principal axis. After reflection, they converge at the focus.
Image: Point-sized, formed at the focus, real and inverted.

2. Object Beyond the Center of Curvature (Beyond C):
The reflected rays intersect at a spot between the focal point and the center of curvature.
Image: Smaller than the object, real and inverted.

3. Object at the Center of Curvature (At C):
The image is formed at the same position as the object.
Image: Same size as the object, real and inverted.

4. Object Between C and F:
The reflected rays meet beyond the center of curvature.
Image: Larger than the object, real and inverted.

5. Object at the Focus (At F):
The reflected rays become parallel and do not meet.
Image: Formed at infinity, highly enlarged, real and inverted.

6. Object Between the Focus and Pole (Between F and P):
The reflected rays seem to be spreading out from a point located behind the mirror.
Image: Enlarged, virtual and upright.

Conclusion:
A concave mirror can form both real and virtual images depending on where the object is placed. Understanding the behavior of light rays using ray diagrams helps in predicting the type and position of the image. These mirrors are useful in various applications where magnification or concentration of light is required.