337. Directions. (A) Measure the resistance of 1 meter of No. 28 German-silver wire. Use the wire as arranged on a board, [Exp. 122] (Figs. 96 and 98), making the connections with the bridge from binding-posts, X and Z. (See [Exp. 129], Note.) The wires connecting the bridge with the ends of the G-s wire will each have to be about 2 ft. long. In making deductions ([§ 330]) figure according to the length used.
(B) Divide the total resistance by 100 to get the resistance of 1 cm. of the wire, and carefully mark off the board into cm. This will give 100 parts between X and Z.
338. Directions. (A) Using the No. 28 G-s wire on the board, as arranged for [Exp. 122], measure the resistance of the 2 meters in series, the connections being made with the bridge from X and Y, [Fig. 98].
(B) Compare the result with that of [Exp. 133]. What is the relation between the length of a wire and its resistance? See Summary of Laws. (See [Exp. 129], Note.)
339. Directions. (A) Measure the resistance of the above two meters of No. 28 G-s wire when joined in parallel. ([§ 293].) The binding-posts, X and Y, can be joined by a short wire with connectors on its ends, or by clamping a thin strip across by means of spring connectors. Use the 2-ohm coil as the standard, and make proper allowances. ([§ 330].)
(B) From the results of Exps. 132 and 135 what can be said about the resistances of parallel circuits as compared with the resistances of the separate branches?