AM) rh'fUiLK.MS 



7. What is the equation of a 110-volt. oO-cvde voltage? What 

 instantaneous value of this voltage when the time is 0.002 sec.? 0.004 sec.? 



8. Plot the squared values of the current wave of problem 1. i. 

 much smaller scale for the squared values, (ai What is the frequem 



-Hiaivd wave? (&) What distance in amperes is its axis above the original 

 iat is its average value? (d) What is the square root of this 

 average value? (<'> What relati between (d) and the maximum 



value'.' 



9. A certain current has an effective value of 20 amp. What is its maxi- 

 mum value? What direct current will produce the same heating in a given 

 ohmic resistance. 



10. A certain direct-current series-arc system is not guaranteed to oper- 

 ate safely .it any voltage in excess of 10,000 volts between wires. This 

 system is later supplied with alternating current by a constant-current 

 transformer. What is the effective value of the highest alternating elec- 

 tromotive force that can be safely used? 



11. Sketch a current and a voltage wave having effective values of 12 

 anil 120 volts respectively and in which the current lags the voltage 



by l~>. If the voltage wave is passing through zero in a positive direction 

 at 1:00 o'clock at what time will the current wave be going through its 

 corresponding phase? 



12. Plot two waves corresponding to currents having effective values of 

 20 and 30 amp. respectively, these two currents differing in phase by 90, 

 the .'30 amp. current lagging. Add the ordinates of these two \vave> point 

 by point and plot the resulting wave, (a) What is its maximum value? 



What i< its effective value? (c) What result is obtained by adding 

 two current vectors of 20 and 30 amp. laid off at right angles? (d) What 

 i- the ;umle between the n-Miltaiit wave and the 20-amp. wave? 



13. kej>eat problem 12 when the two waves differ in phase by 60. 



14. Two generator coils generate 200 volts- and 400 volts respectively. 

 The-e two voltages differ in phase by 120, the 200 volts leading. If con- 

 nected in series what is the voltage across their open ends? 



15. If the 400-volt coil is reversed the two voltages now differ in phase by 

 60. Find the resultant voltage. 



16. If both coils, problem 11. gen.Tiite 200 volt*, find the resultant 



Volt 



17. Repeat problem Hi except t! t he voltage coils is reversed, 

 making the two voltages differ in phase by 60. 



QUESTIONS ON CHAPTER II 



1. How may the power in an all eriiat ing-current circuit be determined 

 at anyii is the gn ..f tin- puer curve 

 voltage and the current an- in pha 



the maximun 



2. In what way does the p- nt in \\ i 



lags <Kr beh, .t in \\hii-h tli. in phase 



with the voltage? What is the average power in such 



