3-29Q-20.In a closed-loop configuration the output signal is determined by (the input signal, the feedbacksignal, both).Q-21.In the inverting configuration, the input signal is applied to the (a) (inverting, noninverting)input and the feedback signal is applied to the (b) (inverting, noninverting) input.Q-22.In the inverting configuration, what is the voltage (for all practical purposes) at the invertinginput to the operational amplifier if the input signal is a 1-volt, peak-to-peak sine wave?Q-23.In the inverting configuration when the noninverting input is grounded, the inverting input is at(signal, virtual) ground.Q-24.In a circuit such as that shown in figure 3-15, if R1 has a value of 100 ohms and R2 has a valueof 1 kilohm and the input signal is at a value of + 5 millivolts, what is the value of the outputsignal?Q-25.If the unity-gain point of the operational amplifier used in question 24 is 500 kilohertz, what isthe bandwidth of the circuit?Q-26.In a circuit such as that shown in figure 3-16, if R1 has a value of 50 ohms and R2 has a value of250 ohms and the input signal has a value of +10 millivolts, what is the value of the outputsignal?Q-27.If the open-loop gain of the operational amplifier used in question 26 is 200,000 and the open-loop bandwidth is 30 hertz, what is the closed loop bandwidth of the circuit?APPLICATIONS OF OPERATIONAL AMPLIFIERSOperational amplifiers are used in so many different ways that it is not possible to describe all of theapplications. Entire books have been written on the subject of operational amplifiers. Some books aredevoted entirely to the applications of operational amplifiers and are not concerned with the theory ofoperation or other circuits at all. This module, as introductory material on operational amplifiers, willshow you only two common applications of the operational amplifier: the summing amplifier and thedifference amplifier. For ease of explanation the circuits shown for these applications will be explainedwith d.c. inputs and outputs, but the circuit will work as well with a.c. signals.Summing Amplifier (Adder)Figure 3-20 is the schematic of a two-input adder which uses an operational amplifier. The outputlevel is determined by adding the input signals together (although the output signal will be of oppositepolarity compared to the sum of the input signals).