ELECTRICAL ENGINEERING PROBLEMS 



PART I 

 CHAPTER I 



ELECTROMOTIVE FORCE, CURRENT, CONDUCTANCE 

 AND RESISTANCE 



1. Given three 110-volt tungsten lamps with resistances of 

 50, 120 and 200 ohms in series, with 330 volts applied across the 

 outside, what will be the difference of potential around each lamp? 

 (3 min.) 



2. Given circuits of 4 and 6 ohms in parallel, and in series with 

 these a circuit of 7.6 ohms. What current will be sent through 

 this combination of circuits by 120 volts? If each of the resistances 

 be halved, what will the current be? (2 min.) 



3. Given two circuits of 5 and 7 ohms in parallel between 

 two points A and B, and in series with these, 10 ohms between 

 B and another point C. If 310 volts be applied between A and 

 C, required the volts between A and B, and between B and C 

 and also the current flowing. (4 min.) 



4. Five 625-ohm, 20-candle-power and four 392-ohm, 32- 

 candle-power, 125-volt tungsten lamps are all in parallel. The 

 resistance of the circuit connecting them to the generator is 2 

 ohms. Find the conductance of each lamp and of the whole 

 group, the current taken by each lamp and the voltage required 

 at the generator to give the lamps their proper current. (8 min.) 



5. Given three circuits of 5, 3 and 1 T 3 T ohms respectively 

 in series, and in series with these, two parallel circuits of 5 and 

 6 ohms. With 360 volts applied to the outside terminals, what 

 will be the pressure on the 3-ohm circuit and what current will 

 flow? If this circuit be changed from 3 to 15 ohms, in what ratio 

 will the drop around the 5-ohm circuit be changed? (3 min.) 



6. The voltage between the terminals of a 6-foot piece of 

 wire is 50 and its resistance is 100; for the calibration of a volt- 



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