Ideal source to load: An ideal 12 V voltage source feeds a 120 Ω load resistor. What is the voltage measured across the load terminals?

Introduction / Context:
This question checks understanding of an ideal voltage source. An ideal voltage source maintains a fixed voltage across its terminals regardless of the load (within the ideal model). Thus, the load voltage equals the source voltage when connected directly without any internal series resistance.

Given Data / Assumptions:

• Ideal voltage source VS = 12 V (zero internal resistance).
• Load resistance RL = 120 Ω.
• Direct connection between source and load, steady-state DC.

Concept / Approach:

For an ideal source, the terminal voltage does not sag under load. Therefore, the potential difference across the load equals VS. The current is I = VS / RL if needed, but voltage remains fixed at 12 V across RL.

Step-by-Step Solution:

Verification / Alternative check:

If there were internal resistance, we would use a divider to find voltage sag. Since internal resistance is zero by assumption, no divider effect exists.

Why Other Options Are Wrong:

'is 0 V' implies a short or open preventing voltage; not applicable. 'is 120 V' confuses voltage with resistance value. 'cannot be determined' is incorrect because the ideal model fully specifies the outcome. 'is 1.2 V' is an arbitrary, unjustified drop.

Common Pitfalls:

Assuming every source has internal resistance; reading 120 Ω as 120 V by mistake; ignoring the explicitly ideal nature of the source.

Final Answer:

is 12 V