Pin functions — classic 741 op-amp (8-pin DIP): For the standard μA741/LM741 op-amp in an 8-pin dual-in-line package, which pin number is the inverting (−) input?

Introduction / Context:
Knowing pin assignments prevents wiring errors that can cause oscillation, inversion mistakes, or device damage. The 741 is a classic teaching op-amp; despite newer devices, its pinout remains a reference pattern for many DIP-8 op-amps.

Given Data / Assumptions:

• Device: 741-family op-amp in 8-pin dual-in-line (DIP) package.
• Standard orientation notch indicates pins counterclockwise from top-left as 1–4 and 5–8.
• Typical supply rails on pins 4 (−V) and 7 (+V).

Concept / Approach:
The textbook 741 pinout is: 1 = offset null, 2 = inverting input, 3 = noninverting input, 4 = −V, 5 = offset null, 6 = output, 7 = +V, 8 = NC. Thus, the inverting input is pin 2 and the noninverting input is pin 3. Other op-amps may differ (especially single-supply or rail-to-rail types), so always check the datasheet.

Step-by-Step Solution:

Verification / Alternative check:
Cross-check any 741 datasheet or lab bench component; continuity from pin 2 to inverting input circuitry confirms the assignment.

Why Other Options Are Wrong:

Common Pitfalls:
Mirroring pin numbers when flipping the IC; confusing SOIC pinouts with DIP; assuming all op-amps share the 741 pinout without checking.

Final Answer:
Pin 2 is the inverting (−) input