Norton’s equivalent current (IN): Is it defined as the open-circuit current between two terminals, or the short-circuit current?

Difficulty: Easy

Correct Answer: False

Explanation:


Introduction / Context:
Norton and Thevenin equivalents are dual representations of a linear two-terminal network. Correctly identifying Norton’s current prevents mistakes when transforming sources or characterizing loads.


Given Data / Assumptions:

  • Linear, bilateral network with independent/dependent sources and resistors.
  • Two terminals under test for equivalent replacement.
  • Standard definitions of open-circuit and short-circuit measurements.


Concept / Approach:

Norton’s current IN is the short-circuit current between the two terminals (with the terminals shorted). Thevenin’s voltage VTH is the open-circuit voltage between the two terminals. The Norton/Thevenin resistance is the same: RN = RTH (under appropriate deactivation rules).


Step-by-Step Solution:

Determine VTH: measure or compute the open-circuit voltage (no load connected).Determine IN: short the terminals and compute the resulting current through the short; IN = ISC.Relate the two: VTH = IN * RTH, and RTH = RN.Hence, IN is not an open-circuit current; it is the short-circuit current.


Verification / Alternative check:

By transformation: if you know VTH and RTH, the equivalent Norton current is IN = VTH / RTH, which numerically equals the short-circuit current you would measure directly.


Why Other Options Are Wrong:

  • Calling IN an open-circuit current confuses it with VTH definition.
  • No averaging is involved; it is strictly the short-circuit current.
  • The statement “divided by the shorted resistance” is unclear; the correct relation is IN = VTH / RTH.
  • Rated power of the load is irrelevant to the definition.


Common Pitfalls:

Using open-circuit current (which is zero in resistive networks) instead of short-circuit current for Norton calculations, leading to erroneous equivalences.


Final Answer:

False

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