Figure 8. Variation of electric field Em with distance R at channel frequency 105 Hz, for a single microcrack ( lc=10-3 m), due to (a) piezo-electric and (b) piezo-magnetic sources. (1) s=10-1/W-m ; (2) s=10-3W-m ; (3) s<10-4/W-m . The breaks in the curves correspond to the limits of applicability of the asymptotic formulas (cf. Figures 2b, c).