IMPEDANCE. 35 



function of the circuit, since the three sides represent the 



quantities C x R,C x 2 IT nL, C x */R- + (2irnL) 2 . Suppose 

 the triangle is re-drawn to a scale such that the' side E { E r 

 instead of representing C R volts, represents R ohms. Then, if 

 the quantities representing the remaining sides are also drawn 

 to this scale, after dividing their value by C, we shall get a 

 triangle similar to the previous one, but drawn to a scale o l r 



I R O 



SCALE of OHMS 

 012 



10. 15. TRIANGLE OF RESISTANCE AND IMPEDANCE. 



ohms instead of volts. This has been done in Fig. 15, where 

 each side of the traingle E i E r , Fig. 10, has been divided 

 by 25 (the current of the circuit), and the whole drawn to the 

 scale of ohms shown below the triangle. For convenience the 

 triangle has been drawn with the side representing the resis- 

 tance horizontal. This direction is the one usually adopted 

 where other circumstances do not afford any reason to the 

 contrary. 



If a circuit has a resistance which is exceedingly small, 

 the value of the impedance becomes practically 2 " w L, i.e., 

 equal to the reactance. If the self-induction is very small, 

 the impedance approximates to the resistance of the circuit. 



It is to be noted that the new triangle has no arrow heads, 

 as the quantities represented by it are no longer variable, 

 and the sides of the triangle do not now represent rotating 

 vectors, but fixed quantities, or scalars. 



The three sides represent respectively 

 01= resistance = R. 

 I R = reactance = 2 TT n L. 

 R = impedance = \/ R- + (2 n L)-, 



the angle of lag of the circuit still being represented by the 

 angle R I = e/>. 



