Series aiding sources: if 6 V and 9 V supplies are connected in series aiding (same polarity), what is the total resulting voltage across the load?

Introduction / Context:
Combining sources in series requires attention to polarity. With series aiding orientation, voltages add algebraically to increase the total emf. This principle is frequently used to obtain higher voltages from multiple cells or batteries.

Given Data / Assumptions:

• Two sources: 6 V and 9 V.
• Connection: series aiding (positive to negative, same polarity aiding).
• Ideal sources with negligible internal resistance.

Concept / Approach:

For series aiding, V_total = V1 + V2. Ensure polarities are aligned so that the individual emfs reinforce rather than oppose each other. No further calculation is needed.

Step-by-Step Solution:

Verification / Alternative check:

Polarity diagram confirms both sources push current in the same direction, so their voltages add.

Why Other Options Are Wrong:

6 V or 9 V ignores addition; 3 V would suggest opposing orientation with a 9−6 difference, not aiding.

Common Pitfalls:

Misreading orientation and subtracting instead of adding; overlooking internal resistance (not relevant here).

Final Answer:

15 V