Question

A student is walking down the hallway when she yells hello from outside and open class room door.Explain how reflection and diffraction can be used to explain why everyone inside the room can hear her voice.

Answer 1

ANSWER and EXPLANATION

We want to explain how it is possible that everyone inside the room can hear the voice of the student.

Due to the laws of reflection, the reflection of sound is comparable to the reflection of light. When a sound wave is incident on a surface, a reflective wave is created, and so, in the hallway, reflected waves are created as the sound wave crosses the hallway and collides with the walls, which causes a portion of that wave to be reintroduced back into the hallway.

When the sound wave arrives at the open classroom door, it is diffracted through the door. This can only occur when an object has dimensions that are closer to or smaller than the wavelength of the sound wave.

In other words, the student's voice bends around the door so, the people in the classroom can hear her voice.