This page has been validated.
298
ELECTROMOTIVE WAVE IN METALS
were taken for maximum effects, starting from 10° and ending in 100°, and backward from 100° to 10°. Effect of hysteresis is very clearly seen (fig. 80, A); there is a considerable divergence between the forward and return curves, the return curve being higher of the two. On repeating the cycle several times, the divergence becomes much reduced, the wire acquires a more constant sensitiveness.
Effect of Annealing.—I repeated the experiment with the same wire, after pouring hot water and allowing it to cool to the old temperature. It will be seen from the
Fig. 80. Cyclic curves for maximum effects due to increasing and decreasing amplitudes of vibration. A, fresh wire; B, after annealing; C, the same after three cycles. Abscissa represents the amplitude of vibration: the ordinate represents the corresponding electromotive variation.
