In order to find R thevenin, I need to find Isc across a and b since there's a dependent source. Based on my calculations, Vth=500/3V. I've spent countless hours thinking about Isc,please help.

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    \$\begingroup\$ Please show all of your work so far. -1 for taking a poor photo and not cropping. \$\endgroup\$ – Elliot Alderson Jan 2 at 12:50
  • \$\begingroup\$ indeed,that was poor from my part,I will use circuit lab. \$\endgroup\$ – doom Jan 2 at 13:05

First of all, I strongly recommend actually assigning names (like \$R_1\ldots R_4\$) to your resistors. It makes talking about schematics much easier.

Anyway, when shorting a-b, your 10 Ω becomes irrelevant.

All the current from the current source goes through that short, so while we have to add that current to the total current through the a-b short in the end, it doesn't interfere with the rest of the calculation. So, you build a "helper" circuit.

Thus, all you have to do is calculate the current through R3 in this circuit:


simulate this circuit – Schematic created using CircuitLab

The voltage across R2 (or across R3) is your v_x; I'm sure you can solve this :)


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