106 EFFECT OF CAPACITY. 



The following experiments illustrate the effect of 

 the various quantities in an alternating circuit possessing 

 capacity upon the impedance. 



EXPERIMENT XVIII. DETERMINATION OF DEPENDENCE 

 OF CURRENT IN A CIRCUIT UPON CAPACITY. 



DIAGRAM OF CONNECTIONS. 



(A) vww 



M l M 2 Source of alternating current. 



R Non-inductive resistance of known value. 



R Variable non-inductive resistance for maintaining 



the voltage of V constant. 

 C Condenser capable of giving several values of 



capacity. 



A Ammeter for measuring current in circuit. 

 V Voltmeter for measuring voltage of portion of 



circuit consisting of C and R. 

 S Switch for breaking circuit. 



Instructions. Connect in series a known non-inductive 

 resistance R, condenser capable of giving several values of 

 capacity, an ammeter, and variable non-inductive resis- 

 tance. Connect a voltmeter across the condenser and 

 resistance R, so as to read the drop in both together. 



Supply the circuit with alternating current, and 

 maintain constant the periodicity and the voltage as read 

 on the voltmeter. 



First, short-circuit the resistance R, so as to read the 

 current in the circuit having capacity and a negligibly 

 small resistance. Take a series of readings, each 

 corresponding to a different value of the capacity. 



Then, for one or two values of the resistance R take 

 similar sets of readings, keeping the resistance constant 

 during each set. 



