Hi,

I'm doing some homework for my circuitry class and I'm stuck. I have to find the value in Vin/Out of a low pass filter that I posted below.



I got the break frequency which I have also shown below, but I do not know how to find the value of Vin or Out. I am also confused by what an octave is, but I think it is adding the same frequency per octave.




Any help would be great

 

Ohm's Law states: V=I*Z
Let us look at your Vc expression. You have Vc=Zc. Why did you remove I? Therefore we know for a FACT that your expression of Vc is wrong.



As far as Vin and Vout. The point of this exercise is to generate a Transfer Function. In your previous schooling, the point was to take known Vin or Vout and find the resulting values. This IS NOT a point NOW.

You have a classic voltage divider. Vin goes into the voltage divider, Vout comes out. Voltage divider is formed by R and Zc. Can you derive an expression (without actually using numbers) to show relationship Vout=(something)*Vin? Can you then apply middle school math and modify that expression into the form of Vout/Vin=(something)?

 

Ohm's Law states: V=I*Z
Let us look at your Vc expression. You have Vc=Zc. Why did you remove I? Therefore we know for a FACT that your expression of Vc is wrong.



As far as Vin and Vout. The point of this exercise is to generate a Transfer Function. In your previous schooling, the point was to take known Vin or Vout and find the resulting values. This IS NOT a point NOW.

You have a classic voltage divider. Vin goes into the voltage divider, Vout comes out. Voltage divider is formed by R and Zc. Can you derive an expression (without actually using numbers) to show relationship Vout=(something)*Vin? Can you then apply middle school math and modify that expression into the form of Vout/Vin=(something)?

That's not what this is. That's Xc, not Vc. It's only a ratio, not actual values for Vin and Vout, I just found that out.