21. The galvanometer is an early instrument used to measure the strength of an electric current. 22. In 1826, Poggendorff developed the mirror galvanometer , a device for detecting electric currents. 23. A Faraday disk can also be operated with neither a galvanometer nor a return path. 24. At the very top was the galvanometer . 25. His research included investigating galvanometers and electricity. 26. Mirror galvanometers were used extensively in scientific instruments before reliable, stable electronic amplifiers were available. 27. Stewart measured radiated power with a thermo-pile and sensitive galvanometer read with a microscope. 28. The vibration galvanometer is used for detecting alternating currents in the frequency of its natural resonance. 29. The old brass and wood instruments, with such odd names as galvanometer , remain perfectly undisturbed. 30. The resulting induction current was transmitted through two wires to the receiver, consisting of a galvanometer .
