Everyone at a party is talking equally loudly. If only one person were talking,

Question

Everyone at a party is talking equally loudly. If only one person were talking, the sound level would be 18 dB. Find the sound level when all 30 people are talking. Answer in units of dB. An experiment requires sound intensity 1.79 W/m^2 at the distance of 3.12 m in any direction from a speaker. What total sound power is required? Answer in units of W. The red light emitted by a He-Ne laser has a wavelength of 633 nm in air and travels at 3.00 times 10^8 m/s. Find the frequency of the laser light. Answer in units of Hz.

Explanation / Answer

008)

sound level is beta = 10 dB*log*(I/Io)

18 = 10*log*(I/10^-12)

I = 6.3 W/m^2

when 30 persons are talking

Intensity is I = 30*6.3 W/m^2

beta = 10*log(30*6.3/10^-12) = 142.765 dB

-----------------------------------------------------

009)

Sound power is P = I*surface area = 1.79*(4*pi*r^2) = 1.79*4*3.142*3.12^2 =219 W

010) speed of light = frequency * wavelength

v = lamda*f

f = v/lamda = 3*10^8/(633*10^-9) = 4.74*10^14 Hz

Related Questions

Navigate

• Browse (All)
• Browse E
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.