The emf of an ordinary lead acid storage cell is dependent on the currents that have been drawn from the cell during the preceding hours. A circuit, using two dry cells and a storage cell, which will maintain a current through a potentiometer constant to better than 0.001% for periods of at least ten minutes, is described. A similar arrangement will provide constant current through two resistances which are to be compared by the potentiometer method.

This content is only available via PDF.
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.