CHAPTER IX. 



ELECTRIC OSCILLATIONS AND ELECTRIC WAVES. 



112. Mechanical and electrical parallels. A great help to the 

 clear understanding of the elementary theory of electricity and 

 magnetism is afforded by the identity of many of the equations 

 of mechanics and electricity as exhibited in the following schedule. 



Translatory Motion 



* = vt (i) 



in which x is the distance 

 traveled in t seconds by a 

 body moving at velocity v. 



W =Fx 



(4) 



in which W is the work 

 done by a force F while 

 the body upon which the 

 force acts moves a distance 

 x in the direction of the 

 force. 



Fv 



(7) 



in which P is the power 

 developed by a force F 

 acting upon a body mov- 

 ing at velocity v in the 

 direction of F. 



W = \m& (10) 



in which W is the kinetic 

 energy of a mass m mov- 

 ing at velocity v. 



F=m ^t (I3) 



in which F is the unbal- 

 anced force required to 



r~~ 



Rotatory Motion 



= wt (2) 



in which <f> is the angle 

 turned in t seconds by a 

 body turning at angular 

 velocity co. 



W = T<f> (5) 



in which W is the work 

 done by a torque T while 

 the body upon which the 

 torque acts turns through 

 an angle about the 

 axis of the torque. 



P = Ta> (8) 



in which P is the power 

 developed by a torque T 

 acting on a body turning at 

 angular velocity w about 

 the axis of T. 



W 



(n) 



in which W is the kinetic 

 energy of a wheel of mo- 

 ment of inertia K turning 

 at angular velocity w. 



in which T is the unbal- 

 anced torque required to 



193 



Electricity and Magnetism 



q = it ( 3 ) 



in which q is the electric 

 charge which in t seconds 

 flows through a circuit 

 carrying a current . 



W = Eq (6) 



in which W is the work 

 done by an electromotive 

 force E in pushing a 

 charge q through a circuit. 



P = Ei (9) 



in which P is the power 

 developed by an electro- 

 motive force E in pushing 

 a current * through a 

 circuit. 



W = 



(12) 



in which W is the kinetic 

 energy of a coil of induc- 

 tance L carrying a cur- 

 rent *. 



in which E is the "unbal- 

 anced" electromotive force 



; PKOPtKiV OF ELECTRICAL LABORATORY,! 



