28 



ELECTRICAL MEASUREMENTS 



nometer is said to be over-damped. When the circuit is broken, 

 the needle returns to zero according to equation (15). Equations 

 (13) and (15) are plotted in Fig. 13 where the values r = 0.2, 

 P = 0.2 and k = 1.0 are assumed. 



01 234 5 6 7 8 9 10 11 12 13 14 tf 16 U 18 19 20 

 lime in Seconds 



0.2 



Showing the Decay 



G; Ivalio 



ieter \ 



Damp 



tne Circuit is 



Deflection 



ng Oonsti nt 



aed 



01234 56 7 8 9 10 11 12 13 14 15 16 17 18 19 2 

 Time in Seconds 



FIG. 13. Illustrating the motion of galvanometer needle. 



Oscillatory Deflection.-When k* < 4 T P, m, and m, are com- 

 plex, that is 



mi = a + jb 

 in* a jb 



