# Sound intensity using decibel values

1. Nov 25, 2009

### 123helpme

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 $$\beta$$= 10 log (I$$_{}2$$/I$$_{}1$$)
and I$$_{}1$$=1.0x10^-12 W/m^2

i have attempted multiple times but cant 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 $$\beta$$ for 100dB and I$$_{}1$$=1.0x10^-12 W/m^2
but from there im not quite sure what to do

2. Nov 25, 2009

### KLoux

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. Nov 27, 2009

### Redbelly98

Staff Emeritus
Welcome to Physics Forums.
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.