THE DIRECT-CURRENT MOTOR 



CM. I 



The force / on the conductor is. as we have seen, 

 /f/ilO" 1 , where 77 is the number of lines per square centi- 

 metre in the plane making 6 degrees with the tangent at d. 

 Substitute for H its value in terms of the intensity in the 



I . , f i 



tangent plane, and we get /= - ~t^ ^ ow ) this 



FIG. 3 



force acts in a direction making 6 degrees with the tangent 

 at d. Hence the resolved part of the force in the direction 



, . Aidn,-, 

 the tangent is 10 a . 

 2?rr 



The sum of the tangential forces on all the conductors 



AiN 

 round one side of the armature is thus - 10" 1 , where N 



