Intensity and dB level

  • Thread starter PCPanos
  • Start date
  • #1
2
1

Homework Statement


The intensity of a certain spherical wave is 8.0 W/m^2 at a distance of 1.0 m from the source. If the medium is isotropic and nonabsorbing, calculate the decibel intensity 100m from the source.

Homework Equations


β=10ln(I1/I0)

The Attempt at a Solution


I know how to use these equations... And to find the original dB level i use
β=(10dB)ln(8.0/10^-12)

Im just not sure what to do to find intensity 100m away?
 

Answers and Replies

  • #2
35,442
11,884
What do you mean with "original dB level"?

How does intensity depend on distance for spherical waves without absorption?
 
  • #3
haruspex
Science Advisor
Homework Helper
Insights Author
Gold Member
2020 Award
36,231
6,842
"Decibel" is very confusing because the term is used both for relative and absolute intensities. As far as I am aware, the unit dB always denotes (or should always denote) a relative intensity. If an absolute intensity is intended then it should be qualified to indicate the reference level, like dBm or dBmW.
Where does your 10-12 come from?
 

Related Threads on Intensity and dB level

  • Last Post
Replies
4
Views
4K
  • Last Post
Replies
8
Views
2K
  • Last Post
Replies
3
Views
17K
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
3
Views
620
  • Last Post
Replies
1
Views
4K
  • Last Post
Replies
1
Views
4K
  • Last Post
Replies
10
Views
3K
  • Last Post
Replies
5
Views
1K
  • Last Post
Replies
4
Views
6K
Top