THE ELECTRICAL CAPACITY OF SIMILAR, NON-PAR- 
ALLEL PLANE PLATES, AND ITS APPLICATION 
WHERE THE PLATES ARE NON-RE CT ANGULAR. 
L. E. DODD. 
An investigation 1 in which it was necessary to find the distance 
between plane, non-parallel plates in terms of their electrical ca- 
pacity raised the question of the amount of error in applying the 
equation for parallel plates. An equation for non-parallel plates 2 
was derived. 
By a special transformation with conjugate functions 3 it is 
shown that in an extensive divided conducting plane, where the 
line of division is straight, if a positive charge resides on the 
conductor on one side of the line, and a corresponding negative 
charge on the other, the lines of force are arcs of coaxial circles 
having the line of division for axis. The equipotentials are thus 
planes passed through the line of division. If two of these equi- 
potentials be taken with a small included angle, and if equal 
and opposite limited areas of the equipotentials be considered, 
figure 33, the case is that of the non-parallel plates in the ex- 
periment, neglecting edge corrections. If the limited areas are 
supposed rectangular the capacity equation is 
C=W/ 4 7r *log(r 2 / rj)'!/ 0 (see figure 35) (1) 
This equation is obtained by assigning definite potentials to 
the two plates and integrating the expression for density of sur- 
Physical Review, Vol. V, No. 1, p. 78, Jan., 1915. 
Physical Review, Vol. IX, No. 1, p. 96, Jan., 1917. 
3 Jeans, Elec, and Mag., 2d ed., sec. 318, p. 268. 
