Doppler effect?

Question

convert a sound intensity of 36 decibels to an equivalent intensity in watts/m ^2?

please explain ste by step how u got it. especially how to take an anti log of a number with the calculator.

Answer 1

Decibels = 10*Log(Intensity/10^-12 Watts/m^2)
36 dB = 10* Log(Intensity/10^-12 Watts/m^2)
3.6 = Log(Intensity/10^-12 Watts/m^2)
10^(3.6) = Intensity /10^-12 Watts/m^2
3981 = Intensity / 10^-12 watts/m^2

3.981*10^-9 Watts/m^2

You can either push the 10^ button on your calculator to do the anti log, or type in 10 and then push the power button.

Answer 2

The Doppler effect does not change the level as much as the frequency. A train at 100 mph and whistle coming toward y the whistle will appear higher in frequency then what it is. At the closets approach is where u would hear the true frequency of the whistle . As it passed it would appear lower in frequency. That is Doppler .We used the same technique to measure satellite actual frequency.

Answer 3

L= sound intensity level
I = intensity
I*= reference intensity (10^-12 W/m^2)

(the symbol ^ stands for the exponent: es. squared meter m^2)

the relation betwwen inesity and sound intensity level is
L=10 log ( I / I* )

that means, dividing for 10
(L / 10)=log ( I / I*).... using antilog
10^(L/10)= (I / I*)... moltiply for I*
I = I* x 10^(L/10)
that's the equation solved..
on the calculator now it's simple using the semplified equation..

I=3.98 x 10^-9 W/m^2

can check even there

Answer 4

36 dB = 3.98x10^-9 W/m²

dB = 10 log I / I0

I is the intensity, I0 is 10^-12 W/m².

Rearrangement:

log I/I0 = dB/10

I/I0 = 10^(dB/10)

I = I0 * 10^(dB/10)