Circuit Theory #32 | Inverting Op-Amp: Gain Formula and 5 V Example

Instructor: Dr. Süleyman Burak ÇELİK

Thirty-second lesson in the Circuit Theory series. In this lesson we solve the inverting op-amp step by step. We start from the actual question: find the output voltage and voltage gain. Then we use virtual ground, zero input current, and equal resistor currents to derive the inverting amplifier formula. Main goals: - Understand why the inverting input node is treated as virtual ground - See why the current through R1 continues through Rf - Derive Vo = -(Rf / R1) Vi without memorizing it - Apply the formula to R1 = 1 kΩ, Rf = 2 kΩ, and Vi = 5 V - Check that Vo = -10 V fits inside the plus and minus 12 V supply rails - Interpret the output sine wave: same frequency, double amplitude, inverted phase