# Charge flow in simple circuits

## 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!

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phinds
Gold Member
2019 Award
Bottom right: No charge can flow through since negative terminal cannot be directly connected to another negative terminal.
RIght answer for the wrong reason. It's perfectly acceptable to connect negative terminals.

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

phinds
Gold Member
2019 Award
I would say it as 2 positive terminals are making up the circuit
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?

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

phinds
Gold Member
2019 Award
The potential on the positive side is maximum. The potential on the negative side is 0?

IntegralDerivative
Here is what I mean:

phinds
Gold Member
2019 Award
IntegralDerivative
I think the potential on each side of the bulb is maximum?

phinds
Gold Member
2019 Award
I think the potential on each side of the bulb is maximum?
Yes, but it's irrelevant whether or not it is maximum, minimum, or anywhere in between. Focus on why no current flows.

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

phinds
Gold Member
2019 Award
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?
Exactly.

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

phinds
Gold Member
2019 Award
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?

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