Kindly explain how to solve the following network. The answer is 6 ohms and independent of R2. Can anyone explain that?

 

Kindly explain how to solve the following network. The answer is 6 ohms and independent of R2. Can anyone explain that?

Remove R2 and you'll see two parallel sets of 6 ohms (3 + 3) in parallel. If you have two resistors (6 ohms each), I can assure you that the equivalent resistance is NOT 6 ohms for the full circuit.

 

Can you solve it now ? ? ?

 

3 ohms...

 

3 ohms...

That's what I'm seeing. Just how the TS knows it's 6Ω is beyond me. Maybe it is. I've always been good at math. There's NO equation I can't screw up!

 

I'll give you a hint: There's no current flowing through the 400Ω resistor.

 

Remove R2 and you'll see two parallel sets of 6 ohms (3 + 3) in parallel. If you have two resistors (6 ohms each), I can assure you that the equivalent resistance is NOT 6 ohms for the full circuit.

Thanks for the reply. Yes, I just misquoted it. The answer is 3 ohms. Really sorry for that. But can you explain how do we arrive at 3 ohms.

 

Kindly explain how to solve the following network. The answer is 6 ohms and independent of R2. Can anyone explain that?

The answer is 3 ohms. Sorry for misquoting.

 

Thanks for the reply. Yes, I just misquoted it. The answer is 3 ohms. Really sorry for that.

I understand it now. You guys are real genius!

 

As I gave you the hint before, the 400Ω resistor has no current. Therefore no voltage. No voltage, no current no apparent resistance. In other words the 400Ω resistor is just a goldbrick circuit. It does nothing to the values.

SO: You have two 3Ω resistors in series - effectively creating a 6Ω resistor. You have a second set of resistors constituting another 6Ω resistor. Two 6Ω resistors in parallel equate to 3Ω. Do you understand how we come up with 3Ω?

 

Can you solve it now ? ? ?View attachment 131895

Yes, I can see that there is no potential difference across 400 ohms. So we eliminate it from the circuit and solve. Is that right?

 

Yes, that's right. It's a goldbrick. Made to make you chase it for no good reason.

 

As I gave you the hint before, the 400Ω resistor has no current. Therefore no voltage. No voltage, no current no apparent resistance. In other words the 400Ω resistor is just a goldbrick circuit. It does nothing to the values.

SO: You have two 3Ω resistors in series - effectively creating a 6Ω resistor. You have a second set of resistors constituting another 6Ω resistor. Two 6Ω resistors in parallel equate to 3Ω. Do you understand how we come up with 3Ω?

Yes, I am 100% clear. Thanks.
I must say you guys are great people.
Are you paid for this?

 

If I were paid it'd probably be 20¢. Used to be 2¢, but given inflation - - - .

But no, we're not paid. Just that some of us are loud mouths and like to help others.

 

Nice job. You can also solve it with 3 loop equations. Set I1, I2 and I3 as clockwise loop currents from left to right, top to bottom.

I changed the I to Y.

e.g.
3Y1+400*(Y1-Y2)+3Y3=0
2 more eqns

 

This thread is solved and closed. Thanks!

 

MOD NOTE: Moved to Homework Help. Closed per TS's request.