Operational Amplifiers (Op‑Amps) — A/L Physics

Operational Amplifier (Op‑Amp) A high‑gain DC-coupled differential voltage amplifier with two inputs and one output. An ideal op‑amp has infinite open‑loop gain, infinite input impedance, zero output impedance, and infinite bandwidth. In practice, it amplifies the voltage difference between its inverting (−) and non‑inverting (+) inputs. Example: Used in audio preamplifiers to boost a weak microphone signal.

Inverting Amplifier Configuration A circuit where the input signal is applied to the inverting (−) input through a resistor, with feedback from output to inverting input. The output voltage is inverted (180° phase shift) and given by V_out = -R_fRin V_in . The non‑inverting input is grounded. The gain is determined solely by external resistors, making it stable and predictable. Example: A sensor signal conditioner that needs to invert and scale a voltage.