Single-node reference — node A is wired directly to the positive terminal of an ideal +10 V DC source, while the negative terminal of the source is the reference ground. What is the voltage at node A with respect to ground?

Introduction / Context:
Reading node voltages relative to a defined reference (ground) is fundamental in circuit analysis. If a node is tied directly to an ideal source terminal, its potential is fixed by that source, independent of loads elsewhere, assuming ideal connections and no series impedance at the tie point.

Given Data / Assumptions:

• An ideal +10 V DC source with its negative terminal at ground (0 V).
• Node A is directly connected to the positive terminal (no intervening elements).
• Wires are ideal with zero drop.

Concept / Approach:
By definition, the potential difference between the source’s positive and negative terminals is +10 V. Ground is 0 V at the negative terminal. Therefore, any node rigidly connected to the positive terminal must be at +10 V relative to ground. This is a direct application of the definition of ideal sources and reference nodes.

Step-by-Step Solution:

Verification / Alternative check:
Place an ideal voltmeter with the black lead at ground and the red lead at node A; it reads +10 V. In simulation, nodal analysis assigns +10 V to any node directly tied to the source positive terminal.

Why Other Options Are Wrong:

Common Pitfalls:
Forgetting to specify the reference node; assuming wire resistance causes drop when the problem states ideal conductors.

Final Answer:
+10 V