# Charge flow in simple circuits

1. May 12, 2017

### IntegralDerivative

1. The problem statement, all variables and given/known data

3. The attempt at a solution

Top left: No charge flowing through circuit b/c switch is open, not closed.
Top right: No charge flowing through circuit b/c circuit does not connect positive and negative terminals
Bottom left: Charge flows through circuit b/c closed loop between + and - terminal.
Bottom right: No charge can flow through since negative terminal cannot be directly connected to another negative terminal.

Please let me know if these answers are correct and how I can make them better. Thank you!

2. May 12, 2017

### phinds

RIght answer for the wrong reason. It's perfectly acceptable to connect negative terminals.

3. May 12, 2017

### IntegralDerivative

Thank you so much for you response phinds! :)

I don't get this. But I would say it as 2 positive terminals are making up the circuit, and they not sending any electrons through the circuit essentially. The electrons are all concentrated at the wire connecting the 2 negative terminals.

4. May 12, 2017

### phinds

No, that is not correct. Everything you see is part of the circuit, it's just a question of whether or not current flows through the various parts (it doesn't).What is the potential on each side of the bulb?

5. May 12, 2017

### IntegralDerivative

The potential on the positive side is maximum. The potential on the negative side is 0?

6. May 12, 2017

### phinds

7. May 12, 2017

### IntegralDerivative

Here is what I mean:

8. May 12, 2017

### phinds

9. May 12, 2017

### IntegralDerivative

I think the potential on each side of the bulb is maximum?

10. May 12, 2017

### phinds

Yes, but it's irrelevant whether or not it is maximum, minimum, or anywhere in between. Focus on why no current flows.

11. May 12, 2017

### IntegralDerivative

There is no potential difference across the bulb so no current can flow. The potential is the same everywhere on the right side of the circuit between the 2 positive terminals?

12. May 12, 2017

### phinds

Exactly.

13. May 12, 2017

### IntegralDerivative

Thank you so much phinds :D I get it now.

14. May 12, 2017

### phinds

Now let me pose another question to extend the problem, and your understanding.

Those are ideal batteries. Now let's consider real-world batteries which have internal resistance. Suppose one of the batteries has a .01 ohm resistor in series with its positive terminal and the other battery has a .012 ohm resistor in series with its positive terminal. Does the answer change?

15. May 12, 2017

### IntegralDerivative

Wow great. :) I will try to solve this after my classes today. Thank you.