I'm trying to find R_NO and solve the problem (b) below, however I'm not getting the right answer. According to the book , the correct answer is R_NO=15ohms, I_NO=2A.
If I short all voltage supplies and open all current sources then the R_NO should be 10ohm || 30ohm = 7.5ohms. Am I doing something wrong?
The current through the voltage source on the left is the same as the current through the 10 Ohm resistor, and we are told that the voltage across it is double the voltage across the 10 Ohm resistor. Thus the voltage source can be replaced by a 20 Ohm resistor.
The rest is easy:
a) 20Ω in series with 10Ω = 30Ω
b) 30Ω in parallel with 30Ω = 15Ω