These days I'm looking at operational amplifiers; from what I've seen, implementing them in a circuit is quite simple, at least when they are connected as "non-inverting". Determining the gain/amplification is possible by doing a calculation of two resistors, R1 and R2 (should R2 be called a "feedback resistor"?)
(The image is taken from http://mustcalculate.com/electronics/noninvertingopamp.php.)
Let me do a practical example to explain where my questions are:
In my example I choose to implement an op-amp (for example, the TLV272, which is also "rail to rail") as "non inverting amplifier". Then I want to increase a voltage of 10 volt to 15 volt (to be sure, I will feed the op-amp with a power supply of 15 volt). Well: by the equation I have to choose a value of 20 kΩ for R1 and a value of 10 kΩ for R2, which is equal to an amplification of 3.522 dB (voltage gain 1.5).
OK, but I could also do the same by choosing R1 as 200 kΩ and R2 as 100 kΩ, or increase these values until R1 of 200 MΩ and R2 of 100 MΩ (or at the totally opposite: R1 of 2 milliohm and R2 of 1 milliohm): in all these cases I will still have a gain of 1.5, but with totally different ranges of resistors, in terms of values.
I can't understand the criteria (in terms of range) how these resistors should be choosen. Maybe this criteria is related to the kind of signal which the op-amp will have to manipulate on his input? Or what else? And in practical example, which will be the difference if I increase a signal using "R1 = 2 kΩ R2 = 1 kΩ" and "R1 = 200 MΩ R2 = 100 MΩ"?
EDIT: I've seen that my question has been edited, also to correct my grammar: thank you. I'm sorry for my misspellings, but english is not my main language. Next time, I will do an attempt to be more accurate in my grammar.