Balance methods in alternating current measurement

THE advantages of opposition or balance methods of measurement, except where speed is the primary requisite, are too well known to require elaboration in this paper. They may be used, not only for measurements where extreme precision is required, but also in the determination of electrical quantities which are too minute to operate instruments of the direct-deflecting type, or which emanate from sources where conditions would be disturbed by the introduction of such instruments. Since alternating-current instruments are of inherently lower sensitivity than those for direct current, it follows that the need for opposition methods of test are more pressing here than where meters of high sensitivity are available.