292. Directions. (A) Without A G in place, take the reading of G V. The current now passes from Cu through 1, M P-B, 2, G V, 3, M P-A, 4 to Zn.
(B) Connect wires 5 and 6 to the plates, as shown by the dotted lines. Again take reading of G V, and compare it with the first reading. Does some of the current pass through A G?
293. Divided Circuits; Shunts. The current divides at M P-B into two parts; one part may be called a shunt of the other. The circuit is said to be divided; it has two branches. If the two ends of a wire be fastened to another as in [Fig. 101], the circuit is also divided. When two or more conductors lead side by side from one point to another, they are called parallel circuits; that is, the conductors are joined in parallel.
As strong currents would injure delicate galvanometers,[116] a small part only of the current may be allowed to pass through the galvanometer by using a shunt. [Fig. 89] shows such an arrangement, in which most of the current passes through the shunt, S. There are many practical uses of shunts.
EXPERIMENT 115. To see what is meant by "short circuits."
Apparatus. About the same as in [Exp. 114], [Fig. 88]. The astatic galvanoscope is not needed; in place of it provide a short piece of metal, such as a battery-plate, or even a jack-knife. Arrange as in [Fig. 88], but without A G.
294. Directions. (A) With the current passing as described in [Exp. 114] (A), take the reading of G V.