demarcation can be drawn between the two; such divisions are somewhat arbitrary. In the case of tin cell we have the two wires originally alike. When one wire is vibrated a difference of potential is observed between the strained and unstrained wires, the P.D. disappearing
Fig. 13.—E.M. variation due to a single vibration through 90°, 180°, and 360° in a Tin cell. Period of vibration, 5″. Thick lines represent effect of stimulus, dotted lines represent the recovery.
when the acted wire recovers from the strain. We may describe the same fact in chemical language by saying that owing to strain there is a tendency of the strained wire to become chemically more active (zinc-like), such tendency lasting only as long as it takes the wire to recover from the strained condition.
6. Increased Effect with Increasing Intensity of Vibration.
In fig. 13 are given the curves of response for single vibration, having amplitudes of 90°, 180°, and 360°, the period being 0·5 second. It will be noticed that the intensity of response increases with the energy of vibration.
