I disagree on those 2 voltages being the same!?
Here http://www.youtube.com/watch?v=ZrMw7P6P2… ,from 4:45 to 5:05, SalmanKhan said that the voltage between the 2 ends of the cell is the same as between the two ends of a resistor that is in parallel.
I disagree. i splits in i1 and i2, so i=i1+i2.
V=i.R , so of course the voltage wouldn't be the same!
Am I wrong?
Here http://www.youtube.com/watch?v=ZrMw7P6P2… ,from 4:45 to 5:05, SalmanKhan said that the voltage between the 2 ends of the cell is the same as between the two ends of a resistor that is in parallel.
I disagree. i splits in i1 and i2, so i=i1+i2.
V=i.R , so of course the voltage wouldn't be the same!
Am I wrong?
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Batteries don't make particular currents. They fix a potential difference, and then an ideal battery supplies whatever current is necessary to maintain that potential difference. And then you are confusing cause and effect. The traditional way of writing "Ohm's Law", V = iR, unfortunately, promotes that confusion, so it's not really your fault. The formula looks like it is saying you run a current i through a resistor (cause), and you get a potential difference V (effect). But that's backward. It would be better to write the equation i = V / R, because what really happens is you apply a potential difference V across a resistor (cause), and you get a current i flowing (effect).
The potential differences across each resistor must be the same as the potential difference across the battery, as there is no potential difference in an ideal wire. There's a wire attached to the left end of the battery. If we follow that wire around, we see that it branches, and connects to the left end of both resistors. Since there is no potential difference in the wire, the left end of each resistor must be at the same potential as the left end of the battery. Also, there's a wire attached to the right end of the battery. If we follow that wire around, we see that it branches, and connects to the right end of both resistors. Since there is no potential difference in the wire, the right end of each resistor must be at the same potential as the right end of the battery. So, if there's a potential difference V between the ends of the battery, there must be the same potential difference V across each resistor.
I hope all the above (which turned out wordier than I'd hoped), answers your last question. Those three situations don't "result" in the same voltage. Those three situations must necessarily have the same voltage, which results in different currents.
The potential differences across each resistor must be the same as the potential difference across the battery, as there is no potential difference in an ideal wire. There's a wire attached to the left end of the battery. If we follow that wire around, we see that it branches, and connects to the left end of both resistors. Since there is no potential difference in the wire, the left end of each resistor must be at the same potential as the left end of the battery. Also, there's a wire attached to the right end of the battery. If we follow that wire around, we see that it branches, and connects to the right end of both resistors. Since there is no potential difference in the wire, the right end of each resistor must be at the same potential as the right end of the battery. So, if there's a potential difference V between the ends of the battery, there must be the same potential difference V across each resistor.
I hope all the above (which turned out wordier than I'd hoped), answers your last question. Those three situations don't "result" in the same voltage. Those three situations must necessarily have the same voltage, which results in different currents.
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A triple Thanku is much better than 5 stars or 10 points! You are very welcome.
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Yes, you are wrong.
The voltages are the same because the 2 points across which the voltage is measured are connected by conductors (Ω = 0) over which no voltage drop can be sustained.
It is a definition that the voltage across resistors in parallel is constant, while series resistors all have the same current.
The voltages are the same because the 2 points across which the voltage is measured are connected by conductors (Ω = 0) over which no voltage drop can be sustained.
It is a definition that the voltage across resistors in parallel is constant, while series resistors all have the same current.
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Gggos