CHAPTER II. 

 ELECTRIC POTENTIAL. 



POTENTIAL. Potential, in the physical sense, is the 

 power to accomplish work. It derives its specific name 

 from the nature of the work, as gravity potential, heat 

 potential, electric potential. 



A pound weight raised to the height of ten feet has 

 acquired ten foot-pounds of gravity potential, and has 

 the power, if allowed to descend to the same level, of 

 accomplishing ten foot-pounds of work, either in rais- 

 ing another weight, or setting machinery in motion by 

 which work may be accomplished. 



A mass of metal whose temperature has been raised 

 from zero to one thousand degrees, has acquired one 

 thousand degrees of heat potential, and can accomplish 

 work to that amount in cooling to zero, either by heat- 

 ing another mass, or generating steam by which machin- 

 ery can be put in motion and work accomplished. 



We have seen that bodies, when electrified, acquire 

 the power to attract or repel other bodies. This power 

 is called electric potential. 



Suppose that the electric energy of the sealing-wax 

 in attracting the balanced rod, represented in Fig. 1, 

 Chapter I., were just sufficient, if expended without 

 loss, to move the rod one foot ; and, in doing so, to 

 overcome a resistance from inertia and friction repre- 

 sented by two ounces (one-eighth of a pound ) ; the 



