Internal Resistance Calculator: Find r Easily

Calculate the Internal Resistance of Your Power Source

Volts (V)
Volts (V)
Amperes (A)

Results

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Internal Resistance (r):

Use our Internal Resistance Calculator to quickly determine the intrinsic resistance of any power source. Simply input the Electromotive Force (EMF), terminal voltage, and current to get accurate results for your electrical circuits.

Formula:

The formula to calculate internal resistance (r) is:

r = (E - V) / I

  • r: Internal Resistance (Ohms, Ω)
  • E: Electromotive Force (EMF) (Volts, V)
  • V: Terminal Voltage (Volts, V)
  • I: Current (Amperes, A)

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