Calculating Battery Internal Resistance: V=IR Method

  • Thread starter Thread starter accol
  • Start date Start date
  • Tags Tags
    Resistors
Click For Summary
SUMMARY

The discussion focuses on calculating the internal resistance of a battery with an electromotive force (emf) of 24V and a terminal voltage of 22V when connected to a 7.5-ohm resistor. The correct internal resistance is determined to be 0.68 ohms. The calculation involves using Ohm's Law (V=IR) to find the current in the circuit and the voltage drop across the internal resistance, which is essential for accurate results.

PREREQUISITES
  • Understanding of Ohm's Law (V=IR)
  • Familiarity with basic electrical concepts such as emf and terminal voltage
  • Knowledge of series circuits and voltage drops
  • Ability to manipulate algebraic equations for problem-solving
NEXT STEPS
  • Study the calculation of internal resistance in batteries using the formula V = I(R + r)
  • Learn about the impact of internal resistance on battery performance and efficiency
  • Explore methods for measuring internal resistance in practical applications
  • Investigate the differences between ideal and real battery behavior in circuits
USEFUL FOR

Electrical engineers, battery technology researchers, and students studying circuit analysis will benefit from this discussion on calculating battery internal resistance.

accol
Messages
6
Reaction score
0
1. A battery is manufactured to have and emf of 24V, but the terminal voltage is only 22V when the battery is connected across a 7.5ohm resistor...what is the internal resistance of the battery?




3. Ok I have the answer already which is .68ohm...but I can't find a way to get to it. At first I tried V=IR or 24=I*7.5 and then plugged that answer into the same equation but with the voltage of 22. I also tried the opposite way. That answer didn't work.

I also tried subtracting the volts from each other to get .27R. Can someone please tell me what I am doing wrong?
 
Physics news on Phys.org
Answer these questions:
What's the voltage drop across the internal resistance?
What's the current through the circuit?
Combine these two answers to find the internal resistance.
 

Similar threads

Mechanisms Involved When Charging a Battery
  • · Replies 10 ·
Replies
10
Views
2K
Finding the internal resistance of battery
  • · Replies 10 ·
Replies
10
Views
3K
Internal Resistance of a Car Battery
  • · Replies 8 ·
Replies
8
Views
13K
Batteries in series, parallel, and internal resistance
  • · Replies 24 ·
Replies
24
Views
5K
Why formula for internal resistance for charging battery v = e + Ir
  • · Replies 3 ·
Replies
3
Views
2K
Unraveling the Mystery of EMF Internal Resistance
  • · Replies 2 ·
Replies
2
Views
2K
Potential difference of an emf with internal resistance
  • · Replies 4 ·
Replies
4
Views
2K
Internal Resistance in a Battery
  • · Replies 3 ·
Replies
3
Views
2K
How to solve for EMF and internal resistance in a circuit?
  • · Replies 8 ·
Replies
8
Views
3K
I''What is the optimal resistance for maximizing battery terminal voltage?
  • · Replies 2 ·
Replies
2
Views
1K