30 PHYSIOLOGICAL PHYSICS. [Chap. in. 



2. Suppose that -the external resistance is now 

 very great in comparison with the internal, which 

 can be neglected ; that is, let E, = o, and connect 

 the six cells again in multiple arc, then 



E E 



C = , ; but R =.- o, .-. C = ~ ; 

 rC r 



6 + r 



i.e. the current is unaffected, is no greater with six 

 cells than with one. 



To put these . results in other words, supposing 

 cells joined in multiple arc, (1) where there is LITTLE 

 EXTERNAL RESISTANCE the strength of the current is in- 

 creased in direct proportion to the number of elements 

 so joined, or (what is the same thing), in direct pro- 

 portion to the size of the plates ; (2) where the 



EXTERNAL RESISTANCE IS GREAT 710 advantage IS 



derived from increasing the number of the cells so 

 joined, or from increasing the size of the plates. 



3. Suppose, again, six cells connected by a thick 

 wire to an apparatus presenting little resistance, that 

 is, consider the external resistance r to be o, and 

 now join the four cells " in series "/ then 



6E 6E E 



that means, no greater advantage is derived from six 

 cells than from one. 



4. Again, let the external resistance be very 

 great, i.e. suppose the internal to be so small in com- 

 parison as to be regarded as o, and join again " in 

 series "; then 



n , _ ~ 



C = .^ -- ; but B = 0, .-. = - - ; 



6K -f r r 



which means that the effect is sixfold. 



