Electricity for public schools and colleges . of a large jar is a relatively large conductor having the outercoating of the jar very near it and opposed to it. These two form one con-ductor at one potential, since they are connected; but the capacity of the firstis negligibly small as compared with that of the second. The charge + Q,distributes itself between these two portions of the conductor in the ratio oftheir capacities. Hence, we may say that very nearly the whole charge, thatwould have passed to earth if the outside of the unit jar had been to earth,\\ ill have passed into the large ja
Electricity for public schools and colleges . of a large jar is a relatively large conductor having the outercoating of the jar very near it and opposed to it. These two form one con-ductor at one potential, since they are connected; but the capacity of the firstis negligibly small as compared with that of the second. The charge + Q,distributes itself between these two portions of the conductor in the ratio oftheir capacities. Hence, we may say that very nearly the whole charge, thatwould have passed to earth if the outside of the unit jar had been to earth,\\ ill have passed into the large jar. (iii.) It requires a certain differ&nce of potential v for a spark to passbetween A and B. If then A is connected with the prime conductor of themachine, and B with the inside of a large jar, we cannot charge this latter upto the full potential of the prime conductor, but to a potential less than thisby the amount v. § 9. Cascade arrangement of Ley den Jars.—P, Q, and R. arethree Leyden ars mounted on insulated stands, arranged in. cascade as indicated in the figure. These jars must be equal incapacity. To insure this we may take one jar of many that arepresumably equal, and then by comparison choose two or moreothers equal to it. If we give a certain charge to our jar chosen,and measure the potential of the inside (when the outside is toearth), this potential ought to fall to one-half when the knob isconnected with that of an uncharged equal jar. This method isemployed in Chapter IX. § 4. But for rough experimental purposes it will be sufficient tochoose the jars as follows. Let an electrical machine be workedfor some time so that it has got into a constant condition. Thencharge the jars in question with a ?/;///yV/r interposed, as shown inthe last section. If the jars refuse further charge after the samenumber of discharges of the unit jar have taken place, then theircapacity will be approximately equal. CH. VI. ELEMENTARY DISCUSSION OF CONDENSERS 89 Having arranged ou
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