ATTRA< I'LATE. 



ico, the resultant attraction of the whole U"in* is 



r,/r 



where / is the radiui of the boundary of the lamina. 



n/r 1 



thewfore 



eforc the resultant attraction 



u-e suppose & to become infinite, we obtain for the at- 

 traction of a; lamina on an external particle, the 



expression 2irpr, which is independent of the distance < 

 attracted particle from the lamina, 



:ie last result we can deduce the resultant attrac- 

 !' a unitbnn plate of finite thickness, but of infinite 



r, suppose the plate 



initelj large number ot laminae, each 



.i-knrss *', t! each lamina acts 



in a strai.u'lit line through the attracted particle perpendicular 



to the surfaces of the plat ia equal to 2irpr. !!. 



esultant attra 11 be found by adding the attrac- 



of the lamina', and will be 2ir/>A, if A be the thickness 



of the \n 



be placed on rior surface of an infinite 



result just f.mn.l will -xpres the attraction t-r 



I- it U placed in the interior of the 

 at a distance h from one of the bounding planes and 

 a the of resultant attraction will be *wp(k' k) 



totcanh the 1 .ue. 



208. By means of the preceding Article we can 

 the resultant attraction of a uniform cylinder on a particle 

 T.8. 18 



