Question

Sound emerges through a doorway, as in the figure. The width of the doorway is 76 cm, and the speed of sound is 343 m/s. Find the diffraction angle ? when the frequency is each of the following.
(a) 5.8 kHz
_______°

(b) 5.8 ? 102 Hz
_______°

Room Vibrating air molecule located in the doorway

Answer 1

Suppose the first maximum (what does it mean in this case?...): m=1

$asin\theta =m\lambda$

$\lambda =\frac{v}{\nu }$

v=speed of sound

a=width of the door

Replace lambda in the first eq and get theta:

(a) theta1~4.6 deg

(b) theta2~53.2 deg.