• Support PF! Buy your school textbooks, materials and every day products Here!

Battery with internal resistor

  • Thread starter jimmyting
  • Start date
  • #1
13
0
[SOLVED] Battery with internal resistor

Homework Statement


What is the current in a 8.25 ohm resistor connected to a battery that has a .21 ohm internal resistance when the potential drop across the terminals of the battery is 6V?


Homework Equations


[tex]R_{s}=R_{1}+R_{2}...[/tex]

[tex]V=IR[/tex]

The Attempt at a Solution


So I believe that the internal resistor can just be considered being in series to the other resistor, allowing me to calculate the equivalent resistor. Then with that, using V=IR, I thought I was able to get the current flowing through the circuit. I got .70921 A
Can someone correct my train of thought?
 

Answers and Replies

  • #2
Hootenanny
Staff Emeritus
Science Advisor
Gold Member
9,622
6

Homework Statement


What is the current in a 8.25 ohm resistor connected to a battery that has a .21 ohm internal resistance when the potential drop across the terminals of the battery is 6V?


Homework Equations


[tex]R_{s}=R_{1}+R_{2}...[/tex]

[tex]V=IR[/tex]

The Attempt at a Solution


So I believe that the internal resistor can just be considered being in series to the other resistor, allowing me to calculate the equivalent resistor. Then with that, using V=IR, I thought I was able to get the current flowing through the circuit. I got .70921 A
Can someone correct my train of thought?
Note that the potential drop across the terminals includes the internal resistance of the battery. The internal resistance of a battery may be depicted thus,
rsint.gif

So the actual emf of the battery is the 6V plus the voltage drop across the internal resistance. Do you follow?

Image courtesy of Hyperphysics
 
Last edited:
  • #3
13
0
Yes I do thank you for your help. Funny that you got the picture off hyperphysics, I was on there trying to read about this
 
  • #4
Hootenanny
Staff Emeritus
Science Advisor
Gold Member
9,622
6
Yes I do thank you for your help.
No problem.
Funny that you got the picture off hyperphysics, I was on there trying to read about this
Hyperphysics is an excellent general physics reference, I'm glad that you chose to look there rather than Wikipedia :rolleyes:
 

Related Threads for: Battery with internal resistor

  • Last Post
Replies
3
Views
907
  • Last Post
Replies
5
Views
12K
Replies
5
Views
4K
  • Last Post
Replies
2
Views
8K
  • Last Post
Replies
14
Views
18K
Replies
6
Views
3K
Replies
4
Views
2K
Replies
7
Views
13K
Top