CHAPTER X.
CONDENSATION OF ELECTRIFICATION.
EXPERIMENT 82. To find whether a large surface will hold more electrification than a small one.
Apparatus. The insulating table (for details, see [Exp. 64]); a large tin basin or pan (not furnished); the electrophorus ([Exp. 68]).
175. Directions. (A) Test the electrophorus and be sure that it is working properly.
(B) As in [Exp. 70], see how many good sparks I T will take from E C (which should be recharged at each trial) before the potential of I T is raised so that it equals the potential of E C.
(C) Carefully set the basin or pan upon I T, then count the number of good sparks you can pass to it from E C (recharged at each trial). Compare the number of sparks necessary to raise the potential of the large surface until it equals that of E C, with the number found in part (B).
176. Electrical Capacity. It takes more heat to raise the temperature of a gallon of ice-water to the boiling point, than it takes for a quart of ice-water. You have just seen that a large insulated surface will take more sparks from a charged body than a small one, before its potential is raised to that of the small one, and to that of the charging body. We say that a large surface has a greater capacity than a small one, the shape and other conditions being the same.
EXPERIMENT 83. To find whether the capacity of a given conductor can be increased without increasing its size.