ELECTROSTATICS 



19 



this relation is expressed by the formula 



- 



(a) Determine the capacity of a condenser formed of two 

 parallel plates each having an area of A square centimeters sep- 

 arated by t cm. of material of dielectric constant K. Fig. 14. 



+ Q 



A Sq. Cm. 



-Q 



FIG. 14. Parallel plate condenser. 



If a difference of potential E is applied between the terminals 

 a dielectric flux ^ is produced passing from the plate of high 



$ 

 potential to the plate of low potential; a positive charge Q = ^~ 



# 



therefore appears on one plate and a negative charge Q = -^ 



on the other; the density of the charge on the plates is q = -j 

 units per square centimeter, and the dielectric flux density be- 



tween the plates is <D = 47rg = 



.. ,. 



-j lines per square centi- 



meter. The thickness of the dielectric is assumed to be so small 

 that the lines of flux travel directly across from one plate to the 

 other. 



ELECTRICAL LABORA 



.ULTY OP APPLIED' SCIENCE. 



