. Practical wireless telegraphy; a complete text book for students of radio communication . OB 4 PRACTICAL RADIO MEASUREMENTS. 211 (6) Example 2.—Calculate the inductance of a coil three inches in diameter, 8 inches inlength, wound closely with No. 26 double silk-covered wire. From the table on page 213 thediameter of No. 26 D. S. C. wire is .02014 inches, hence, 8 n = ■ = 397 turns; = centimeters;a =: — = ^ = , and from Fig. 196bK = () X (397)= Therefore L = 4^ X , or 3,820,000 centimeters. 22 iT2-6-i:i~-Scr-Sl. itFig. 231—Curves
. Practical wireless telegraphy; a complete text book for students of radio communication . OB 4 PRACTICAL RADIO MEASUREMENTS. 211 (6) Example 2.—Calculate the inductance of a coil three inches in diameter, 8 inches inlength, wound closely with No. 26 double silk-covered wire. From the table on page 213 thediameter of No. 26 D. S. C. wire is .02014 inches, hence, 8 n = ■ = 397 turns; = centimeters;a =: — = ^ = , and from Fig. 196bK = () X (397)= Therefore L = 4^ X , or 3,820,000 centimeters. 22 iT2-6-i:i~-Scr-Sl. itFig. 231—Curves Showing the Value of a Constant for the Ratio of the Diameter of a Wire to Its Pitch. In the curves of Fig. 230, values of K are given for coils lying between those of infinitelength and those where the diameter is 9J/2 times the length This covers all conditionsencountered in practice. (c) Correction factor.—For practical calculation the foregoing formula is sufficientlyaccurate, but for greater precision a correction factor must be applied. In fact, the inductancevalues obtained in examples 1 and 2 are termed the current sheet inductance, based uponthe assumption of a coil wound with infinitely thin tape, the turns of which are assumed totouch but not to be in electrical contact. Dr. Rosa of the Bureau of Standards has given an expression for circular sectioned non-magnetic wire as follows: If the true inductance is designated as L, and the current sheetinductance as L-s, then, L = L-s — L-cwhere L-c is the correction value, and, L-c
Size: 2155px × 1160px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1917
