Alright, I'm getting pretty confused on this problem and don't really know how to start it.

Here it is: http://books.google.com/books?id=ZzHudUMb7WAC&pg=PA678&lpg=PA678&dq=%22Determine+the+value+required+for+R2&source=web&ots=78W_Bd8CX5&sig=Um1IQQCC8sSULdoaWSMuaGqKAHk&hl=en&sa=X&oi=book_result&resnum=1&ct=result#PPA678,M1

Its on page 678 14.20

any help getting me started would be awesome.

edit: I got 2.5 for R2. can anyone confirm this answer?

Thanks

 

R2 is not equal to 2.5.

Hint: You know that when dealing with an opamp, the opamp will always tend to drive/adjust its output to a voltage that results in the two input terminals having the same voltage on them.

The problem states that the output voltage of the opamp is to be assumed zero.

All of this means that you know the DC voltage that is applied to the input. You also know the voltage that is on the negative terminal. And finally you know the voltage that you need on the output of the opamp.

You have all of the ingredients for determining the current flowing in R1. And you should know that the current flowing into the negative terminal of the opamp is zero since it has a very high input resistance. That means that all of the current flowing in R1 is going to end up flowing in R2.

Hopefully this helps you solve the problem.

hgmjr

 

Thanks solved it: 10k ohms i hope

 

10K, That's it.

Good Job!

hgmjr