A parabolic reflector changes a spherical wavefront into which type of wavefront?

A parabolic reflector is designed to focus waves, such as light or radio waves, that come towards it in a spherical wavefront and redirect them into a parallel beam. This transformation is a key feature of parabolic reflectors, which are commonly used in satellite dishes, telescopes, and in lighting applications.

When a spherical wavefront, which expands outward from a point source, encounters the parabolic surface, the unique shape of the parabola causes the waves to reflect off the surface in such a way that they become parallel. This is known as producing a plane wavefront. The parallel waves are essentially flat with uniform phase fronts, which is different from the diverging or curved wavefronts.

This ability to convert spherical waves into plane wavefronts is why parabolic reflectors are so effective in concentrating signals or light beams in a specific direction, ensuring maximum efficiency in transmission and reception applications.