Engineering Converting to a circuit's Thevenin equivalent?

[Jayalk97]

Homework Statement

Homework Equations

Finding the Thevenin equivalent?

The Attempt at a Solution

I found the thevenin resistance to be 185/47 ohms, which came out to be correct.

I've been struggling with this question all day. I ended up attempting to find the norton equivalent and then converting it, since the question asks for both anyways. I started with a source conversion on the 3A and 5ohm current source and resistor, turning it into a 15V voltage source and a 5 ohm resistor in series (going into the b terminal). I shorted the a-b terminal and used KVL to find the current going through as 3A, typed that into my webwork page and it said I was wrong. Is there anything I'm missing here?

 

[gneill]

Are you given values for $I$ and $R$ ?

 

[Jayalk97]

Oh yeah sorry, I = 2.5A and R = 4.5ohms

 

[Jayalk97]

Are you given values for $I$ and $R$ ?

On that note actually, these problems look fairly straightforward and I'm afraid that I misunderstand something fundamental about circuits...

 

[gneill]

Oh yeah sorry, I = 2.5A and R = 4.5ohms

Okay.

Hint: Work from left to right towards the output, converting and combining sources and resistances as you go.

 

[Jayalk97]

Okay.

Hint: Work from left to right towards the output, converting and combining sources and resistances as you go.

If I have a voltage source>resistor>voltage source>resistor in series could I just rearrange and combine them? If so I converted the leftmost current source and resistor to a voltage source in series with it, combined the 2 resistors and voltage sources to get 25.25V and 18.5 ohms. I converted those to a current source in parallel with a resistor to get 101/74A and 18.5ohms. Adding those to the current source in parallel with the resistor on the right I get 121/74A (pointing down) with 185/47ohms, giving me a voltage difference of 605/94 but the program says that is incorrect...

 

[Jayalk97]

Okay.

Hint: Work from left to right towards the output, converting and combining sources and resistances as you go.

Oh my god it explicitly wanted the voltage from a to b, and that is -605/94. I've been trying to figure this out for four hours... Thank you for the help haha.

 

[gneill]

Oh my god it explicitly wanted the voltage from a to b, and that is -605/94. I've been trying to figure this out for four hours... Thank you for the help haha.

Glad to help!