Two converging lenses of unequal focal lengths can be used to reduce the aperture of a parallel beam of light without losing the energy of the light. This increase the intensity. Describe how the converging lenses should be placed to do this.

We know that, refraction through a convex lens, leads to a converging beam. So, placing the second convex kens within range of first one’s focus will make the aperture reduced and also won’t lose energy.