Video Transcript
The following figure shows parallel
incident light rays reflecting from a convex mirror. Do the reflected rays converge or
diverge?
First of all, recall that rays are
said to be convergent if they converge at a point and are said to be divergent if
they move further and further away and will never meet. Now, we are going to draw a diagram
and compare the angles to check whether the rays are spreading apart or converging
together.
Let’s redraw the diagram given to
us, which is a convex mirror, with its optical axis and the center of curvature
labeled. We can see the pink incident ray on
the optical axis and the three incident rays, which we’ll call A, B, and C, are
parallel to each other and also to the optical axis, but at different vertical
distances. We are going to draw the lines
normal to the surface of the mirror at each point where the rays contact the
mirror. Then, we can use the law of
reflection, which states that the angle of reflection must be equal to the angle of
incidence.
Moving upward from the optical
axis, from the labeled vertical distance one to two to three, we can see that the
angles between the reflected rays and the optical axis increase, as shown by angles
a, b, and c. So this tells us that the reflected
rays are divergent, reflecting at larger and larger angles away from the optical
axis as the vertical distance of the incident ray from the optical axis
increases.
