0
\$\begingroup\$

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?

Improve this question
\$\endgroup\$
15
  • 1
    \$\begingroup\$ What is the internal resistance of the battery you are using? \$\endgroup\$ – HandyHowie Apr 18 '19 at 11:45
  • \$\begingroup\$ Are you talking about a real battery or an ideal model of a battery? \$\endgroup\$ – Elliot Alderson Apr 18 '19 at 11:46
  • \$\begingroup\$ @ElliotAlderson An ideal model \$\endgroup\$ – BeastCoder2 Apr 18 '19 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\$ – BeastCoder2 Apr 18 '19 at 11:50
  • \$\begingroup\$ On the datasheet possibly - data.energizer.com/pdfs/nh22-175.pdf \$\endgroup\$ – HandyHowie Apr 18 '19 at 12:02
1
\$\begingroup\$

"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.

Improve this answer
\$\endgroup\$
2
  • \$\begingroup\$ Where could I find internal resistance? \$\endgroup\$ – BeastCoder2 Apr 18 '19 at 12:00
  • \$\begingroup\$ @BeastCoder2 On the datasheet possibly - data.energizer.com/pdfs/nh22-175.pdf \$\endgroup\$ – HandyHowie Apr 18 '19 at 12:05
0
\$\begingroup\$

It would be if the battery you are using could supply that much current.

Improve this answer
\$\endgroup\$
2
  • \$\begingroup\$ where could you find out how much current a battery could supply? \$\endgroup\$ – BeastCoder2 Apr 18 '19 at 11:50
  • 2
    \$\begingroup\$ This answer could be greatly improved with more explanation. Maybe describe why a battery could or could not supply that much current. \$\endgroup\$ – evildemonic Apr 18 '19 at 15:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.