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Alrighty let's pretend that the circuit contains no resistance other than the battery internal resistance and the wire's resistance itself,

Would this be a correct algorithm? (Using OHM'S law)

BR - Battery internal resistance
WR - Wire Resistance

V / (BR + WR) = A

I am just trying to understand the basics before diving into more of the mechanics of our crazy world.

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  • \$\begingroup\$ You've got the division upside-down. Voltage should be on top. \$\endgroup\$ – Dan Laks Jan 26 '17 at 4:28
  • \$\begingroup\$ Yep, that's ohms law! You got it. You won't have a lot of resistance though, so that means a LOT of current. Not so good an idea, but a great place to start. \$\endgroup\$ – Brian Dohler Jan 26 '17 at 4:33
  • \$\begingroup\$ It's "I" not "A". "I" is the formulaic representation of current and a current of 5 amps would also be called 5 A. You did say you were trying to understand the basics so, best learn the proper way to write things before they become a bad habit. I would also call the resistors RB and RW (or Rb and Rw or better still \$R_B\$ and \$R_W\$. \$\endgroup\$ – Andy aka Jan 26 '17 at 8:18
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You've got it basically right.

The only complication in the real world is that neither of those resistances are static. Both the internal resistance of the battery and ohmic resistance of the wire will increase as a function of temperature. And if you short out a battery, you're likely to get a large increase in temperature in both components.

Lithium batteries have this neat feature where if you short the terminals together, it activates the nearest fire truck in your town.

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  • \$\begingroup\$ Needed that laugh! But did not know about the temperature thank you! \$\endgroup\$ – Trevin Corkery Jan 26 '17 at 4:40
  • \$\begingroup\$ ... in fact the internal resistance of a battery is so non-constant, that we tend to measure it by drawing a current from the battery, measuring the voltage drop, and calling the ratio the internal resistance. \$\endgroup\$ – Neil_UK Jan 26 '17 at 7:21
  • \$\begingroup\$ @Neil_UK How else would you measure resistance? \$\endgroup\$ – user253751 Jan 26 '17 at 8:13
  • \$\begingroup\$ @immibis exactly. If it's a battery, forget about calling it a constant, just measure it. If it's a length of quaternary alloy at constant temperature, then you can call it a constant and work out what the current should be for a given voltage. \$\endgroup\$ – Neil_UK Jan 26 '17 at 9:00

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