Plane wavefronts travel toward a concave (curved) barrier as shown. What happens to the wavefronts after they are reflected from the barrier?
Question 1 Report
Plane wavefronts travel toward a concave (curved) barrier as shown.
What happens to the wavefronts after they are reflected from the barrier?
Answer Details
A concave (converging) barrier acts like a concave mirror for waves. When plane wavefronts strike a concave surface, the shape of the barrier causes different parts of each wavefront to reflect at slightly different angles, all directed inward toward a single point called the focal point.
This is the same principle used in satellite dishes and parabolic reflectors: the curved surface collects parallel incoming waves and concentrates them at the focus. The reflected wavefronts become curved (converging) rather than remaining flat.
The wavefronts do not remain plane after reflection because the barrier is curved, not flat. A flat barrier would produce plane reflected wavefronts. They also do not spread out as circular wavefronts - that would require a convex barrier. And they certainly do not pass through unchanged, since reflection reverses their direction of travel.
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