Convex Mirror

 

Convex spherical mirrors are made from a section of an outer silvered ball.

The image formed in a convex mirror is always erect, virtual and diminished in size.

Constructing a ray diagram for a convex mirror

  • A ray travelling parallel to the principal axis virtually emanates from the virtual focal point after reflection by the mirror. To draw the reflected ray you have to put your ruler on the principal focus on the far side of the mirror and the point where the ray hits the mirror. Draw a dashed line from the virtual focus point to the mirror edge and then a solid line for the reflected ray.
  • A ray that aims at the virtual centre of curvature of the mirror is reflected back along its own path. Put your ruler on the object point and at C (or 2F) on the far side of the mirror. Draw a dashed line from C to the mirror and then a solid line to represent the ray that gets reflected back along its own path.
  • A ray that aims at the virtual focal point as it goes towards the mirror will be reflected back along a path parallel to the principal axis Put your ruler on the object point and the far focal point. Draw a solid line to represent the incident ray from the object point to the mirror and then a dotted line to the focus. Now draw a reflected ray that goes from the point your incident ray hit the mirror parallel to the principal axis. Continue that with a dashed line on the far side of the mirror.
  • The point where these three dashed lines meet is the image point.