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How come I always see videos with what seems like a random amount of mA flowing from a battery with a certain amount of voltage?

For example, what if a wire had 0.13 ohms resistance and a battery had 5V electrical difference. That would mean that 38 Amps should be the current (right?).

I=V/R
I=5V/0.13ohms
I=38A (about)

Okay, so I'm editing this now using internal resistance, of about 1ohm.

This gives about 4.5A, so is this correct?

Why are common schematics showing some amount of mA shouldn't it be something like what I've shown, or do they have hidden resistors?

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    \$\begingroup\$ What is the internal resistance of the battery you are using? \$\endgroup\$
    – HandyHowie
    Apr 18, 2019 at 11:45
  • \$\begingroup\$ Are you talking about a real battery or an ideal model of a battery? \$\endgroup\$ Apr 18, 2019 at 11:46
  • \$\begingroup\$ @ElliotAlderson An ideal model \$\endgroup\$ Apr 18, 2019 at 11:48
  • \$\begingroup\$ @HandyHowie it isn’t a real battery but if it were would I just be able to find it on the battery itself? \$\endgroup\$ Apr 18, 2019 at 11:50
  • \$\begingroup\$ On the datasheet possibly - data.energizer.com/pdfs/nh22-175.pdf \$\endgroup\$
    – HandyHowie
    Apr 18, 2019 at 12:02

2 Answers 2

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"So why isn't it?", while solving circuits we assume the wires to have zero resistance, otherwise it's specified that the resistance of the wire isn't zero and also the value of that resistance is given. If it were a real battery it would have some internal resistance, so simply add the internal resistance to the total resistance of the circuit, in your case the resistance of the wire and calculate the current the way you did it before.

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  • \$\begingroup\$ Where could I find internal resistance? \$\endgroup\$ Apr 18, 2019 at 12:00
  • \$\begingroup\$ @BeastCoder2 On the datasheet possibly - data.energizer.com/pdfs/nh22-175.pdf \$\endgroup\$
    – HandyHowie
    Apr 18, 2019 at 12:05
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It would be if the battery you are using could supply that much current.

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  • \$\begingroup\$ where could you find out how much current a battery could supply? \$\endgroup\$ Apr 18, 2019 at 11:50
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    \$\begingroup\$ This answer could be greatly improved with more explanation. Maybe describe why a battery could or could not supply that much current. \$\endgroup\$ Apr 18, 2019 at 15:16

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