Electronic parallel voltage sources exercises?

[I like Serena]

Going back to this:

Io is in fact the current that flows in all across the last circuit I made, right?

Though I recognize it splits here


when it gets back to point a, does it kinda recombine and spits again? I'm not sure how to explain it...

Do you know what I mean?

When you merge the resistors, you can't "see" Io anymore.
You can calculate the voltage drop and the total current though.
Afterward you have to go back to the original circuit to find Io.

 

[Femme_physics]

Forgot to answer

What's so confusing about it?
Or is it just that you didn't see it before?

Yes, it's because I've never seen it before.

I do know that mA means miliampere! I just wanted to know to which it belongs, and now you say it belongs to neither..

so those blue arrows are ANOTHER 3 unknowns?

http://img832.imageshack.us/img832/2659/bluecw.jpg

Uploaded with ImageShack.us

 

[Femme_physics]

When you merge the resistors, you can't "see" Io anymore.
You can calculate the voltage drop and the total current though.
Afterward you have to go back to the original circuit to find Io.

I see, so after I find I_total, I find V. And after I find V I just doV/R1 to find IoYes?

 

[I like Serena]

Well, they are not all really "unknown" are they?
I think the leftmost one is 6 mA, don't you?
That doesn't sound "unknown" to me.

 

[I like Serena]

I see, so after I find I_total, I find V. And after I find V I just do


V/R1 to find Io


Yes?

No, you will have to use KCL to find Io.

 

[Femme_physics]

Well, they are not all really "unknown" are they?
I think the leftmost one is 6 mA, don't you?
That doesn't sound "unknown" to me.

Oh, right *smacks forehead*

No, you will have to use KCL to find Io.

Alright, I see, give me a few moments to try and solve it...be right back with a scan

 

[Femme_physics]

Well I'd hate to start solving this 5 eq 5 unknown thing, but this is it right? I mean, this is what it boils down to?

http://img197.imageshack.us/img197/9635/800cir.jpg PS Maybe a mod can move this topic to the homework section?

 

[Femme_physics]

Well, they are not all really "unknown" are they?
I think the leftmost one is 6 mA, don't you?
That doesn't sound "unknown" to me.

Good point! lol... that was kinda silly of me.

Okay then... should be easy ...hope I'm not oversimplifying it (which I tend to do)...

http://img714.imageshack.us/img714/6847/600il.jpg

 

[I like Serena]

Well I'd hate to start solving this 5 eq 5 unknown thing, but this is it right? I mean, this is what it boils down to?

PS Maybe a mod can move this topic to the homework section?

You can do it this way, but I think you would prefer the "smooth ride".

After calculating I_total, don't go back right away to your original circuit, but take the top diagram you drew in your scan, where you have 2 merged resistors.

There you can determine the voltage drop to the middle.

Only then, go back to the original circuit and calculate all the currents with Ohm's law.

Then, finally apply KCL to find Io.

 

[Femme_physics]

You can do it this way, but I think you would prefer the "smooth ride".

After calculating I_total, don't go back right away to your original circuit, but take the top diagram you drew in your scan, where you have 2 merged resistors.

There you can determine the voltage drop to the middle.

Only then, go back to the original circuit and calculate all the currents with Ohm's law.

Much easier indeed! Well, I doubt we'd have somethign that difficult on the test thankfuly, and speak of the devil... I'm off to college in a jiffy wish me luck

XoX

Edit: Actually I don't want too early, I'll try and solve it

 

[I like Serena]

Good point! lol... that was kinda silly of me.

Okay then... should be easy ...hope I'm not oversimplifying it (which I tend to do)...

No, that won't work.

In your loop (a) you treat the current source of 3 mA as a voltage source of 3 V.
But that is not right.
The corresponding voltage drop is unknown.

 

[Femme_physics]

You can do it this way, but I think you would prefer the "smooth ride".

After calculating I_total, don't go back right away to your original circuit, but take the top diagram you drew in your scan, where you have 2 merged resistors.

There you can determine the voltage drop to the middle.

Only then, go back to the original circuit and calculate all the currents with Ohm's law.

Then, finally apply KCL to find Io.

http://img834.imageshack.us/img834/9089/wttt.jpg


Uhh...okay what am I doing wrong?

btw got less than 30 minutes

 

[I like Serena]

I wish you luck!

 

[I like Serena]

Uhh...okay what am I doing wrong?

btw got less than 30 minutes

Go back to the original circuit.

Now you have the voltage drop between a and b, so you can calculate the currents through the left and right resistor.

Same for b and the bottom.

 

[Femme_physics]

Well this is my last attempt due to time shortage but I don't see how I find Io in any of this:

http://img607.imageshack.us/img607/589/lastattempt.jpg

 

[I like Serena]

Well this is my last attempt due to time shortage but I don't see how I find Io in any of this:

Good!
Do the same between a and b to find I1 and I2.


Aftward apply KCL at point B to find Io.

 

[Femme_physics]

GOT IT!
http://img9.imageshack.us/img9/8990/500xx.jpg
Well, just a few more minutes left so really got to go now, thanks for that last boost of confidence! *HUGS!*

 

[Studiot]

I didn't notice you were doing this one, you and ILS are getting very slick and quick.



Meanwhile someone else is studying the same problem here

https://www.physicsforums.com/showthread.php?t=513513&page=3

post#10 has a good solution.

go well

 

[I like Serena]

It seems that thread didn't have such a smooth ride!