Two Loudspeakers Are Placed Next to Each Other and Driven

question 77

Multiple Choice

Two loudspeakers are placed next to each other and driven by the same source at 500 Hz.A listener is positioned in front of the two speakers and on the line separating them,thus creating a constructive interference at the listener's ear.What minimum distance would one of the speakers be moved back away from the listener to produce destructive interference at the listener's ear? (The speed of sound = 340 m/s. )

• A)1.36 m
• B)0.68 m
• C)0.34 m
• D)0.17 m

---

Definitions:

Lower Explosive Limit

The minimum concentration of a vapor in air below which propagation of flame does not occur on contact with a source of ignition.

Lower Explosion Level (LEL)

The lowest concentration of a gas or vapor in the air that will ignite and produce a flame.

Vapor Phase

The state of a substance when it is in gas form, especially when it coexists with its liquid or solid phase.

Avogadro's Law

States that equal volumes of gases at the same temperature and pressure contain the same number of molecules.