# Need some help to solve these problems.

#### Nazmul Hossain Nihal

Joined Oct 19, 2017
20
Hi,
I can anyone help me to solve these two problems?

#### MrAl

Joined Jun 17, 2014
8,609
Hi,

What methods do you normally use, like nodal or something?
If you know nodal analysis you can write equations for the circuit and solve for what you need.

Is this homework?

#### Nazmul Hossain Nihal

Joined Oct 19, 2017
20
Thanks for your reply, can you please give me some hints from where to start and how?

Yes this is a homework.

#### WBahn

Joined Mar 31, 2012
26,398
MOD NOTE: Moved to Homework Help.

#### crutschow

Joined Mar 14, 2008
28,529

#### MrAl

Joined Jun 17, 2014
8,609
Thanks for your reply, can you please give me some hints from where to start and how?

Yes this is a homework.

Hi,

Well it would help me and others here to help you if you told me what kind of analysis you have done in the past that way we can save time and get right into it in the best way for you.

Do you know Ohm's Law?

#### Nazmul Hossain Nihal

Joined Oct 19, 2017
20
Can you guys calculate the answers for me so that I can check if my calculations are right?
So far I have got Vo in 07 is 60v.

Thank you.

#### LesJones

Joined Jan 8, 2017
3,647
I do not agree with your result of 60 volts for Vo.

Tip. Write down the equation for the current through the 2K and 4K resistors.

Les.

Last edited:

#### WBahn

Joined Mar 31, 2012
26,398
Can you guys calculate the answers for me so that I can check if my calculations are right?
That's not how it works. For all we know, all you are being asked to do is input the answers into a field on a website, so having someone else calculate the answer and tell it to you is the same as simply doing your work for you.

So far I have got Vo in 07 is 60v.
This is a step in the right direction, but all we can really do is tell you yes or no. If you are not correct, then we can't even begin to provide any feedback on what you might be doing right or wrong because you've given us nothing to work with from which to see what you are doing at all.

In this case the answer is no, that is not correct. But I have no idea what you did wrong because I have no idea how you arrived at that wrong answer.

What I can tell you is that you need to start learning how to check your own answers for correctness. This is usually pretty easy to do on engineering problems, even in the real world.

For instance, you claim that Vo = 60 V. That means that the current flowing 4 kΩ resistor is 15 mA, which is also the current flowing through the 2 kΩ resistor yielding 30 V across it. That means that Vs is 90 V. That, in term, means that I0 is 30 mA. That makes the current in the dependent current source 120 mA, of which the other three branches account for a total of 10 mA + 15 mA + 30 mA or 55 mA. So you have 65 mA of current unaccounted for and hence know that the answer is wrong.

It works a WHOLE lot better if you show your best effort to work the problem so that we can see what you are doing and identify at what point you are going wrong. That way we can focus on overcoming issues on that specific point so that you can move forward productively.

#### Nazmul Hossain Nihal

Joined Oct 19, 2017
20
I am really stuck. Can anyone solve these and give me a picture please?

Thank you.

#### BR-549

Joined Sep 22, 2013
4,938
Ok......with the information given.......can you tell me what I8, the current thru the bottom 2 ohm resistor is?

#### Nazmul Hossain Nihal

Joined Oct 19, 2017
20
Ok......with the information given.......can you tell me what I8, the current thru the bottom 2 ohm resistor is?
No, I don't know. The picture is what I have as question. I don't have any additional information.

#### BR-549

Joined Sep 22, 2013
4,938
Alright....the bottom 2 ohm resistor has 0 volts at the bottom of it and 4 volts on the top of it.......what does the 4 volts across that resistor tell you about the current thru that resistor?

#### Nazmul Hossain Nihal

Joined Oct 19, 2017
20
2A. So I8 = 2A? right?

#### BR-549

Joined Sep 22, 2013
4,938
Yes.....which way is the current flowing thru the resistor?

#### Nazmul Hossain Nihal

Joined Oct 19, 2017
20
From D to E

#### BR-549

Joined Sep 22, 2013
4,938
ok.....there is a 3 amp current source feeding 3 amps to the top of the resistor.....but only 2 amps out the bottom.....where did that other amp go?

#### Nazmul Hossain Nihal

Joined Oct 19, 2017
20
I7 = -1 A

#### BR-549

Joined Sep 22, 2013
4,938
I was afraid that would mess you up. It would not be a negative 1 amp. It's just an amp. If I had 3 apples and took two away......I wouldn't have a negative apple left. That one amp is flowing into the battery. That arrow for I7 indicator in the picture is wrong. Conventional current is flowing into the negative terminal of the battery.

Now if I put the negative terminal of an 8 volt battery on 4 volts......what will be the positive terminal voltage.....with respect to point E?