1. ## Proportions

Hi all,

OK...I feel kinda silly asking this....If A is proportional to B how would you put it into a mathematical expression?

The HW problem is this:
"The intensity of a pure tone is proportional to the square of its amplitude. At the time that the initial amplitude has been divided by 1000 what is the value of I/I0, the ratio of the current intensity to the initial intensity?"

Thanx for the help!

2. "A is proportional to B"
A -------> B
A = k(B) -------the mathematical expression
where k is the constant of proportion

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For the posted problem,
Let A = amplitude
So, Ao = initial amplitude

Ao = Ao
A = (Ao) /1000

Io = k(Ao)^2
I = k(A)^2

I /Io = k(Ao /1000)^2 / k(Ao^2)
I /Io = 1 / (1000)^2
I /Io = 1 / 1,000,000 -----------------answer.