Laboratory exercises to accompany Carhart and Chute's First principles of physics . laws may be determined in the laboratory by theuse of simple apparatus and a little patient observation. Experimental: Arrange the apparatus as in Fig. 51, placing the bridge(i?) about 60 cm. from the fixed end (.A). Add enoughweight to stretch the wire tight so that the wire will givea clear note when it is plucked. 1A G fork (frequency 384) would be recommended for this experimentin preference to the A fork, were it not for the relative cheapness of thelatter. 130 LABORATORY EXERCISES (a) Law of
Laboratory exercises to accompany Carhart and Chute's First principles of physics . laws may be determined in the laboratory by theuse of simple apparatus and a little patient observation. Experimental: Arrange the apparatus as in Fig. 51, placing the bridge(i?) about 60 cm. from the fixed end (.A). Add enoughweight to stretch the wire tight so that the wire will givea clear note when it is plucked. 1A G fork (frequency 384) would be recommended for this experimentin preference to the A fork, were it not for the relative cheapness of thelatter. 130 LABORATORY EXERCISES (a) Law of Lengths*—Set the string AB vibratingby plucking it with your first finger. Strike a C tuningfork (frequency 256) on a flat cork, and note whether ornot the fork and the wire give sounds of the same unison can be told by the absence of beats. If thesounds are not in unison, increase the tension by addingmore weight, and try again. Continue in this manneruntil unison is obtained, shifting the bridge a little, ifnecessarjr. Then the string and the fork are making the B. Fig. 51. same number of vibrations per second. Measure andrecord the length AB of the string which gives 256 vi-brations per second. With the tension remaining the same, adjust the lengthof the vibrating string so that it is in unison with an Afork (frequency 426). Do this by moving the and record the length of the vibrating wire. Isthis wire which gives 426 vibrations shorter or longer thanthe wire with the frequency of 256 ? Again vary the length of the vibrating wire so as tobring it into unison with a Cf fork (frequency 512).Measure and record. How does this length compare with LAWS OF VIBRATING STRINGS 131 the length of a string which makes half as many vibra-tions per second, the tension remaining the same ? (5) Law of Tensions. — Record the weight which inPart (a) gave the tension on the wire with a frequency of512. Keeping the vibrating wire the same length, grad-ually decrease
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectphysics, bookyear1913
