In: Physics
Moe, Larry, and Curly stand in a line with a spacing of d = 1.50 m . Larry is 3.00 m in front of a pair of stereo speakers 0.800 m apart, as shown in the figure(Figure 1) . The speakers produce a single-frequency tone, vibrating in phase with each other.
What are the two lowest frequencies that allow Larry to hear a loud tone while Moe and Curly hear very little?
Express your answers using two significant figures separated by a comma. (kHz)
The answer is close ot .48, 1.499 but I keep getting it wrong
if given that
distance between the curly and larry or moe and larry is d = 1.60 m
distance between observers and screen L = 3.00 m
a = 0.800 m
path difference for Lary is zero, so always
constructiveinterference.
path difference for the other 2 is
Δ =√[L2 + (d +a)2] - √[L2 + (d - a)2]
=√[(3.0 m)^2 + (1.60m + 0.40 m)^2 -√[L2+ ( 1.60 - 0.40 m)2
= 0.3755 m
for distructive interfernce λ/2 or 3λ/2 are condition
path difference for small value Δ = λ/2
0.3755 m = λ/2
λ = 0.7511m
frequency f = v/λ
= 343 m/s/ 0.7511 m
= 456.66 Hz
for next value Δ = 3λ/2
0.3755 m = 3λ/2
λ = 0.250 m
frequency f = v/λ
= 343 m/s/0.250 m
= 1.372 kHz