If you're seeing this message, it means we're having trouble loading external resources on our website.

If you're behind a web filter, please make sure that the domains *.kastatic.org and *.kasandbox.org are unblocked.

Main content

Potentiometer: emf & internal resistance of batteries

Problem

A battery with internal resistance of 1 Ω and an unknown emf drives a current across a 9 Ω resistor.
When a potentiometer with a wire AB is connected across the battery, the balancing length is, AE=80 cm.
What do we need in order to find the emf of the battery, E, in the fewest steps of calculation?
Note: Let's begin from scratch, and avoid using any derived results.
Choose 1 answer: