CH. I 



THE INDUCTION FACTOR 



Since the torque in Kquatiun 5 is that due to the action 

 of a current in the armature, we must be careful that we 

 do not credit either the frictional or hysteresis torque to 

 this action ; we must therefore deduct the pull observed 

 with no current in the armature from all subsequent 

 readings, and if the magnet current be kept constant we 

 shall then get the true torque due to the current in the 

 armature. 



Fio. 4 



An ammeter should be placed in the magnet circuit 

 ;ind the current kept constant during the test. The 

 induction l;ict<>r obtained will be that for this particular 

 cimvnt in the magnets; if this current is altered, a 

 ditl'.-rent induction factor will be obtained. 



The experiment here described, in which the induc- 

 tion factor is found by measuring the torque when 



