# Power gain

Discussion in 'Homework Help' started by Michael Pouncil, May 29, 2013.

1. ### Michael Pouncil Thread Starter New Member

May 28, 2013
1
0
Is there anyone out there to help with this....

prep test problem...I can do part a); but not sure about how to go about b), c) or d)

circuit ...Vin +/- with a 150 ohm resister and a 50nF capacitor in series closed and grounded, the Vout +/- is across the capacitor (...for a low pass filter?..it think) Now I am not sure I can do this, it seems like a pretty small voltage for Vout; IR=V, with V= 7.6E-6V ...At this point I am sort of lost.

a) find the circuit's cutoff frequency...got that .. 21220Hz

b)find the circuits gain at 25kHz.

c) find the angle theta of the circuit ( the angle by which Vo leads Vi) at 25kHZ.

d) if Vi=5 angle 25 degrees volts at 25kHz, the the magnitude and phase of Vo.

2. ### WBahn Moderator

Mar 31, 2012
23,848
7,379
Where are you coming up with V=7.6E-6V?

Show your work, otherwise we have to rely on our mind reading abilities and/or crystal balls.

You should express your frequency using scaled units so that sig figs can be better shown, so instead of 21220Hz, write it as 21.2kHz (you aren't justified anything more than three sig figs and arguably only two).

What do you know about the gain at the cutoff frequency? Would you expect the gain at 25kHz to be significantly different from that? Would you expect it to be more or less than that?