Sound intensity using decibel values

In summary, the speaker is having trouble with their sound ISU and their teacher is unable to help. They need to find the sound intensity for decibel values of 100dB and 55dB using the equation \beta= 10 log (I_{}2/I_{}1). They have attempted multiple times but are unable to come to the correct answer and the textbook only provides the answers without solutions. The speaker has substituted the values for \beta and I_{}1, but is unsure of what to do next. They are seeking help from others.
  • #1
123helpme
1
0
okay so I am having trouble with my sound ISU (independent study unit). Though my teacher said he would help, when i asked he said he cant...

what i need to find is the sound intensity for the following decibel values..
a) 100dB
b) 55dB

now the only relevant equation would be [tex]\beta[/tex]= 10 log (I[tex]_{}2[/tex]/I[tex]_{}1[/tex])
and I[tex]_{}1[/tex]=1.0x10^-12 W/m^2

i have attempted multiple times but can't seem to come to the correct answer
the textbook gave the answers but no solution
a)0.10 W/m^2
b) 3.2x10^-7 W/m^2

a) what i tried was subsituting [tex]\beta[/tex] for 100dB and I[tex]_{}1[/tex]=1.0x10^-12 W/m^2
but from there I am not quite sure what to do

help me please!
 
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  • #2
You'll need to post more details. What answers are you getting? What did you try? Show step-by-step. Also, check that you copied the book answer correctly for (a).

-Kerry
 
  • #3
Welcome to Physics Forums.
123helpme said:
a) what i tried was subsituting [tex]\beta[/tex] for 100dB and I[tex]_{}1[/tex]=1.0x10^-12 W/m^2
but from there I am not quite sure what to do

help me please!
You're on the right track. Can you post the equation you get when you make that substitution? You are trying to find I2 in the equation.
 

FAQ: Sound intensity using decibel values

1. What is sound intensity?

Sound intensity is a measure of the power of sound waves per unit area, expressed in watts per square meter (W/m²). It is a measure of the energy that sound carries through a given area per unit time.

2. What are decibels (dB) and how are they related to sound intensity?

Decibels (dB) are a unit of measurement used to quantify the intensity of sound. They are logarithmic and represent a ratio of two sound intensities. The relationship between decibels and sound intensity is logarithmic, meaning that a small change in decibel value represents a much larger change in sound intensity.

3. What is the formula for converting between sound intensity and decibel values?

The formula for converting between sound intensity (I) and decibel values (dB) is: dB = 10 log (I/I0), where I0 is the reference intensity of 10^-12 W/m². This formula is used to calculate the decibel value of a given sound intensity, or to convert a decibel value back to its corresponding sound intensity in watts per square meter.

4. How is the decibel scale used to measure sound intensity?

The decibel scale is used to measure sound intensity because it allows us to represent a wide range of sound intensities in a more manageable and easy-to-understand format. The decibel scale is logarithmic, so each increase of 10 decibels represents a 10-fold increase in sound intensity. This makes it easier to compare and understand different sound intensities.

5. What are some common examples of sound intensity levels in decibels?

A whisper is typically around 30 dB, normal conversation is around 60 dB, and a lawnmower is around 90 dB. A rock concert can reach 120 dB, and a jet engine can produce sound intensities up to 140 dB. Exposure to sound levels above 85 dB for extended periods of time can be damaging to our hearing.

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