# What Is the Power of a Sound Source Emitting 80dB at 30m?

• DylanB
In summary, the sound source emits uniformly in all directions and produces a sound level of 80dB at a distance of 30m. Using the equations for sound intensity and power, the power of the emitting source is calculated to be 1.13W. However, this answer is not listed as a choice and it is possible that the answer given is actually 1.13 x 10^-4W, which is equivalent to 1.13W. Good luck with the exam!
DylanB

## Homework Statement

A sound source emits uniformly in all directions. It produces a sound level of 80dB at a distance 30m. What is the power of the emitting source. (W)

## Homework Equations

dB = 10log(I/Io)

Io = 10^(-12) W/m^2

I = P/A

## The Attempt at a Solution

80dB = 10^(-4) W/m^2

sound disperses in a sphere..

I = P/(4*pi*r^2)

P = 10^(-4)*4*pi*(30)^2

= 1.13W

This answer is not listed, although multiples of it, 2.26, 3.39, 4.52 are choices.

oo well, I think you did it right. I also get same thing =P
See the answers carefully , you will notice that a) is 13 and things on left side are erased, so it must be 1. on the left!

Anyways, good luck with the exam tomorrow!

P.S. funny how I also got stuck on the same question.

ah i see it. I found it odd that I was getting a wrong answer for the easiest question on the exam. thought maybe Rohan was playing tricks on me.

yeah good luck yourself (seems to be a good share of waterloo students here), no more bell curve anymore to take away the wrong answers!

## 1. What is the difference between power and intensity?

Power refers to the rate at which energy is transferred or work is done, while intensity refers to the concentration of power over a given area. In simpler terms, power is the amount of energy produced or consumed per unit time, while intensity is the strength or magnitude of that power.

## 2. How do you calculate power and intensity?

Power is calculated by dividing the amount of work done by the time it takes to do that work. Intensity is calculated by dividing the power by the area over which it is being applied.

## 3. What are the units of measurement for power and intensity?

The units for power are watts (W) or joules per second (J/s), while the units for intensity are watts per square meter (W/m^2).

## 4. How does power and intensity affect different systems or objects?

Power and intensity can affect systems or objects in different ways depending on the amount and concentration of energy being transferred. For example, high power and intensity can cause damage or destruction to materials or living organisms, while lower levels may have no noticeable effect.

## 5. What are some real-life examples of power and intensity?

Power and intensity can be observed in various aspects of everyday life. Some examples include the power output of a car engine, the intensity of sunlight on a sunny day, the power consumption of household appliances, and the intensity of sound from a speaker. In medical sciences, power and intensity are also used in treatments like radiation therapy.

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