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4.6 Norton’s Theorem (1)
It states that a linear two-terminal circuit can be replaced by an equivalent circuit of a current source IN in parallel with a resistor RN,
Where
 
• IN is the short circuit current through
  the terminals.
 
• RN is the input or equivalent resistance
  at the terminals when the independent
  sources are turned off.
The Thevenin’s and Norton equivalent circuits are related by a source transformation.