For a Diffraction Horn Loudspeaker,sound Emerges Through a Rectangular Opening

Multiple Choice

For a diffraction horn loudspeaker,sound emerges through a rectangular opening.The opening of a diffraction horn has a width of 0.12 m.If the speaker emits a continuous tone with a wavelength of 0.09 m,at what angle does the first minimum occur?

A) 47°
B) 39°
C) 23°
D) 12°
E) 66°