72 TREATISE ON ALTERNATING CURRENTS. 



Answers. 1. Energy current = O39t' ; 



wattless = 0-92i. 



3. Energy current = bi ; 

 wattless = 0-865i. 



4. Energy current = 0'866.; 

 wattless =0 6i. 



6. A non-inductive resistance -of 100 ohms is placed in series with a resist- 

 anceless inductance of 0'05 henry. If a P.D. of 1000 volts is applied between 

 the terminals of the arrangement, how is the fall of potential distributed, the 

 frequency being 100 ? 



Answer. Fall of potential along resistance = 954 volt?. 



inductance = 299 '8 



7. If in Question 6 the inductive part had a resistance of 50 ohms, how would 

 the fall of potential be distributed ? 



Answer. Fall of potential along non-iuductive resistance = 652*53 volts. 

 inductive = 384-99 



8. A non-inductive resistance of 10 ohms is placed in parallel with a resist- 

 anceless inductance of 0'025 henry. A P.D. of 100 volts is applied between 

 their common terminals, the frequency being 80. What current flows in the two 

 branches, and what in the main circuit? 



Answer. Current in non-inductive resistance = 10 amperes. 

 Current in inductance = 7 '958 amperes. 

 Total current = 12-78 amperes. 



9. A non-inductive resistance of 10 ohms is placed in parallel with an induc- 

 tive resistance whose self induction is 0'025 henry, and resistance 5 ohms. A 

 P.D. of 100 volts is applied between their common terminals, the frequency being 

 80. What current flows in the two branches, and what is the total current ? 



Answer. Current in non- inductive resistance = 10 amperes. 

 Current in inductive resistance = 7*394 amperes. 

 Total current = 14-467 amperes. 



10. What is the impedance of the combination in Question 9 ? 

 Answer. 6'9 ohms. 



11. If two coils having self-inductions L lf L 2 respectively, and, having 

 negligible resistances, are connected in parallel, what is the self-induction of the 

 combination ? 



Answer. 



12. If the coils in Question 11 have self-inductions 05 and 0'025 respectively, 

 what is the self-induction of the combination ? 



Answer. 0'01G7 henry. 



13. If two coils having resistances of 1 and 2 ohms respectively, and self- 

 inductions of 0'05 and 0-1 henry respectively, be connected in parallel, what is 



