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Why isn't electricity flowing through this wire? 
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#1
Mar1813, 08:07 PM

P: 19

In the top circuit, electricity doesn't flow through section 2, but it does in section 1. In the bottom circuit however, electricity flows through both sections 3 and 4. Why does simply adding a resistor stop the flow of electricity in 2? Much appreciated! 


#2
Mar1813, 08:14 PM

P: 25

current will flow through the easiest path ( without resistance) or with less resistance and as the wire doesn't have any resistance, all the current will flow through it.



#3
Mar1813, 08:20 PM

P: 19




#4
Mar1813, 08:25 PM

P: 25

Why isn't electricity flowing through this wire?
yeh it will, but the one with more resistance will have less current flowing through it.



#5
Mar1813, 08:29 PM

P: 19

Thanks for the help by the way, I greatly appreciate it. 


#6
Mar1813, 08:34 PM

P: 25

it's just how it is, because current has to flow through both of the sections and that most current will flow through the section with less resistance.



#7
Mar1813, 08:38 PM

P: 19




#8
Mar1813, 08:47 PM

P: 25

glad you understood it, your welcome.



#9
Mar1813, 09:09 PM

P: 497




#10
Mar1813, 09:25 PM

Sci Advisor
PF Gold
P: 2,595

Dave 


#11
Mar1813, 09:58 PM

Mentor
P: 22,281

The problem here is one of starting assumptions. If the assumption of the problem is that there is no resistance in the wires (a common assumption), then all of the current has to go through the short. But in real life, there is a finite resistance even in a wire, so a certain amount of current will flow through each branch.



#12
Mar1813, 10:46 PM

P: 335

If you measure the voltage at 2 points on a wire without resistance you get the same result. By short circuiting the resistor in section 2 you are making both ends the same voltage.
The current in an element like a resistor obeys the following: [Voltage (one end)  Voltage (other end) ] / resistance = current So as you can see if the voltages are the same you get zero current. 


#13
Mar1913, 12:31 PM

P: 555

Look up "Current Divider" on Wikipedia. It will explain what is going on quantitatively. If you have a mind for math, this may help you understand better.



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