DESIGN OF CHOKING COILS. 



89 



TABLE II. 



HYSTERESIS Loss. 



Since the induction in the core is 14,000 lines per square 

 centimetre, the hysteresis loss in ergs per cubic centimetre per 

 cycle is 8650. 



The volume of the iron is 1089 c.cms. ; therefore the total loss 

 in ergs per cycle is 



9,419,850 



To provide for this requires 



47'1 watts 

 and takes a current of 



0*51 ampere at 91*6 volts. 



As this current is only 9 per cent, of the total current, the loss of 

 energy in the choking coil is but small. 



The same remark applies for the energy current required for 

 the eddy -current losses. 



]>y working at a lower induction in the iron, and by making 

 the magnetic circuit open instead of closed, the losses may be still 

 further diminished. 



PROBLEMS ON CHAPTER X. 



1. What is the self-induction of a coil of negligible resistance that, when 

 placed in series with a non-inductive apparatus taking 10 amperes at 40 volts, 

 will allow the arrangement to be used on a 100-volt 50-freqnency circuit ? 



Ansiver. 0*029 henry. 



