Question

A beam of light is converging towards a point. A parallel-sided glass slab is introduced in the path of this beam. How will the point of convergence be shifted? Draw the ray diagram.

Answer 1

Initially, the light beam converges at point O. When a parallel-sided glass slab is placed in its path, the light rays get laterally shifted due to refraction inside the slab. This causes the beam to now converge at a new point I, which is farther from O than before. The beam’s convergence direction remains the same, but the convergence point shifts farther because of the sideways displacement caused by the glass slab, as shown in the ray diagram.