Question

Explain the meaning of the terms focus and focal length in case of a convex mirror, with the help of a suitable ray diagram.

Answer 1

Hint: A convex mirror has a curved reflecting surface that bulges out towards the light source. This protruding surface reflects light outwards rather than focusing it. Since the focal point (F) and the centre of curvature (2F) are imaginary points in the mirror that cannot be reached, these mirrors create a virtual image. As a consequence, pictures are formed that cannot be projected on a frame since they are formed within the mirror. At a point, the illusion is smaller than the object, but once the object approaches the mirror, the image becomes bigger.

Complete answer:
A convex mirror's focal point, after reflection from the mirror, is a point on the principal axis where incident light rays parallel to the principal axis tend to arrive. The focal length of a convex mirror is the distance between the fixation and the convex mirror's pole.

By placing a convex lens between the object and the convex mirror, the focal length of the convex mirror can be calculated. When the convex mirror mirrors the rays along the same direction, i.e. when the rays fall naturally on the mirror, a reflection can be obtained with the aid of a convex lens side by side with the object. The difference between the projector and the mirror is then determined by the mirror's radius of curvature, $R$.

Note: Convex mirrors are used in automobiles because they have an upright reflection and a larger field of view due to their angled outwards design. Hospitals, hotels, classrooms, restaurants, and apartment complexes all have convex mirrors in their hallways.