Sign of Focal Length of Concave Mirror

Explanation:
Concave mirrors are converging mirrors that have a focal point where parallel rays of light converge after reflecting off the mirror. The focal length of a concave mirror can be positive or negative, depending on the position of the object in relation to the mirror.

Positive Focal Length:
When an object is placed beyond the center of curvature of a concave mirror, the focal length is considered positive. In this case, the image formed is real and inverted. The focal length is measured from the mirror surface to the focal point along the principal axis.

Negative Focal Length:
When an object is placed between the mirror and its focal point, the focal length of the concave mirror is negative. In this scenario, the image formed is virtual and upright. The focal length is still measured from the mirror surface to the focal point along the principal axis, but the sign is negative to indicate the direction of light rays.

Conclusion:
In summary, the sign of the focal length of a concave mirror is a crucial indicator of the characteristics of the image formed. Understanding the sign conventions helps in predicting the nature of the image based on the object's position relative to the mirror.

Focal length of concave mirror is negative.