INDUCTIVE CIRCUITS IN SERIES AND PARALLEL 66 



50. Required the inductive e.m.f. of a choke coil to be placed 

 in series with a projection arc lamp taking 15 amperes at 35 volte 

 when used on a 110-volt circuit, tin- resistance of the roil being 

 J ohm. If 60 110-volt, }-ampere lamps arc in parallel with tin- 

 above, and with each other, what will be the total rurn-nt? (8 

 raw.) 



51. A 5-ampere arc lump is to be used on :\. 7..">-ampere constant- 

 current line. Its power factor is xr>.(>' ,' and its terminal e.m.f. 

 72 volts. A choke coil with u resistance o'f 2 ohms is to by-pans 

 the remaining current. Construct the diagram and determine 

 the current in the coil and the power factor of the combination 

 (7 rain.) 



52. It is required to measure the exciting or no-load current 

 of a ^-kw. transformer on a 120-volt circuit. In order to adjust 

 the voltage a voltmeter with 800 ohms resistance and negligible 

 reactance is in parallel with the transformer so that the ami; 

 reads its current also. The total current is 0.45 ampere with a 

 power factor of 79%. What is the exciting current and its power 

 factor? (3 min.) 



