en. ii MOTION 



he right of*/, tli,- li,-:it writ t* is the sum nf the 

 line watts and the mechanical war 



This diairmtn illustrates how the difffrenc*- U-twe.-n tli.- 



line watte and the heat watte increases from nothing at .. 



to a maximum at it. ami decreases again to nothing at /. 



iir that when the dynamo is acting as a motor tin* 



f doing work i> n maximum when tin- cunvnt is 



equal to 



Fleming's rulea f-r determining the direction of 

 the force on a conductor and of th- induced tension will IM> 

 found useful. ( 'nmjtaiv Vi^. \~2. lxt the first finger. th- 

 miil'il'- fin^r. ami the thumb of the right hand be held at 

 right angles to one another to represent three rectangular 

 axes; then if tin- tir-t finger point in th> dinvtion of the 

 linet of force, and the motion lx in tin- direction of tin- 

 thiirnl). the middli* finp-r ^iv.-s th.- direction of tin- 

 imltioed tension, i.f. the din>rtion in which th<- induced 

 current would How if it w,-r- f ! io <!.. so. We have 

 already seen that this does not ^iv- th.- lirc<-tion of the 

 current in all case*, since in a motor th- curn-nt does not 

 How in th ilin*-tion of the induced tm-i.-n. 



The necessary complement of the preceding rule in 

 the following: Let the first finger, the middl> finder, and 

 the thumb of the left hand U- h.-l.l at rii/ht angles to one 

 another; thn if th.- direction of the first finger represent 

 that of thi lim-M of force, and the direction of the second 

 finger represent that of the current, tin- thumb will p. .im 

 in tin- direction of tin- forre produce<l by th- :i<-tioM of tin- 

 ournMit on the magnet ir ti.-M. It do*>s not follow that 

 this ix the directinn of the motion, since when the dynamo 

 acte as > generator th>- iiiri-cti< -n of motion ix opposed to 



