Law of Tensions

Abstract

POSSIBLY many science teachers find some little difficulty in satisfactorily demonstrating to a class the “law of tensions” for vibrating strings. In practice, unless the sonometer is fixed vertically, the error introduced by friction at the pulley (especially with heavy weights) is so great that the real tension is very different from that represented by the weight attached. Even if the apparatus be thus fixed, the changing of the weights occupies time, and a comparison wire is necessary, which must first be tuned to exact unison. The following admirable and very simple method was suggested to me by one of my students, and possibly there are some teachers to whom the idea is new.