709 



on the horizontal 'j axis give the frequencies of the alternating 

 current, tliose on the vertical axis 10 times the double deviation in 

 centimeters. 



For the calculation we each time used two points at the same 

 height combined with the ordinate of the highest point of the curve. 

 If for shortness' sake we put 



4;. 7, 



-^^'^ 

 it follows from (15) that 





*"'"•<!: + 4.^ 



Now, if M, O wj and 10^ «[^ io„) are the two values of m corre- 

 sponding to the same amplitude |«j we iuxve the equations 



By elimination of tu„ and y. from these and from 



\a\m 

 we tind 



l«r l«l m 



Let I' be the difference in fre(|uenc3' of the two chosen points, 

 so that tDj — tu., =z 4.^1' and let us put 



|aim 

 Then we find, after introducing the value of ft 



A = .V-|«|„,.v|/^-^. ..... (17) 



When the resonance curve has been drawn, (17) gives a value 

 of /. foi' each ordinate [rtj. If this value or what amounts to the 





is constant, this proves that the influence of the 



damping can really be represented by a linear term in the equation 

 of motion. 



The following table contains the values of r and h, taken from 



the diagram and those of r L/ ^ we have deduced from them. 



') If the figiue is brought into tlie right position by a rotation of 90°. 



