Solve Rth for Circuit | Get Expert Help Now

[GBA13]

Homework Statement

Hi,

I am trying to find Rth for this circuit but I am not sure if I've got it right, could someone give a hand?

Homework Equations

The Attempt at a Solution

I think R3 can be omitted and R1, 2, and 4 are in series so the answer is 10k Ohms as R5 is in parallel to what was the power source (now a wire) can be omitted as well?

Thanks!

 

[gneill]

R3 cannot be omitted as there is no path from A to B that can avoid it.

What's the procedure for finding the Thevenin resistance of a circuit?

 

[GBA13]

Really? I thought that when Vt has been replaced by a wire (as you do to fine Rth) then all the current can go through the new wire instead?

 

[gneill]

Inject a current at A and show how it can get to B without passing through R3. Shorting the voltage supply (replacing with a wire) does not make a difference there. It does, however, let you eliminate another resistance...

 

[GBA13]

Oh sorry, I'm getting confused with R5. (You can get rid of R5 can't you?)

 

[gneill]

Oh sorry, I'm getting confused with R5. (You can get rid of R5 can't you?)

Yup. Suppressing the voltage source shorts out R5, so their combined resistance is 0 Ohms.

 

[GBA13]

So then R1 and R4 are in series and that pair is in parallel to R2. That whole combination is then in series with R3 to make Rth 5.4 k Ohms? :)

 

[gneill]

So then R1 and R4 are in series and that pair is in parallel to R2. That whole combination is then in series with R3 to make Rth 5.4 k Ohms? :)

Yes!

 

[GBA13]

Yes!

Yay! Thanks very much! :D