Illustration of Potentiometer

1841 Potentiometer

The book of science

Tom Sharp

Johann Christian Poggendorff electromagnetism Illustration of Potentiometer


To measure an unknown voltage, Johann Christian Poggendorff taught to compare a fraction of a larger known voltage from sliding the contact on a resistive wire until a galvanometer shows zero between them.

Null balancing

To evict an ear worm I have at the ready exactly as many notes of Will Holt’s “Lemon Tree” as it takes to displace the worm without getting “Lemon Tree” stuck in there. Some worms are more persistent, and some less, but “Lemon Tree” has all the power I need to displace anything else.

Variable potential

Turning on the heat Increasing the pressure Stepping on the gas Upping the ante We carefully calibrate every adjustment trying just hard enough working only so hard playing only so hard hoping just enough.

A galvanometer measures electric current. A Wheatstone bridge uses a galvanometer to measure resistance. A potentiometer use a galvanometer to measure voltage.

See also in The book of science:

Readings in wikipedia: