States that a large active element may be thought of as millions of tiny, distinct sound sources.

States that a large active element may be thought of as millions of tiny, distinct sound sources.

• A. Huygens principle
• B. Snell's law
• C. Faraday's law
• D. Inverse square law

Answer: (A)

This statement relies on Huygens' principle: a wavefront can be treated as the envelope of many tiny secondary wavelets emitted by every point on the front. In acoustics, a large active element like a speaker diaphragm can be modeled as a collection of millions of tiny sound sources, each radiating sound. The overall sound field is the sum of all those wavelets, which naturally explains how the wavefront propagates and how diffraction and interference patterns arise. That’s why a big element behaves like many small sources. The other options describe different ideas: refraction at boundaries (Snell’s law), electromagnetic induction (Faraday’s law), and how intensity falls off with distance from a point source (inverse square law). They don’t capture the concept of constructing a wavefront from numerous sources on the front itself.

This statement relies on Huygens' principle: a wavefront can be treated as the envelope of many tiny secondary wavelets emitted by every point on the front. In acoustics, a large active element like a speaker diaphragm can be modeled as a collection of millions of tiny sound sources, each radiating sound. The overall sound field is the sum of all those wavelets, which naturally explains how the wavefront propagates and how diffraction and interference patterns arise. That’s why a big element behaves like many small sources.

The other options describe different ideas: refraction at boundaries (Snell’s law), electromagnetic induction (Faraday’s law), and how intensity falls off with distance from a point source (inverse square law). They don’t capture the concept of constructing a wavefront from numerous sources on the front itself.