. Physical laboratory experiments : mechanics, optics and heat. the time requiredfor a body to fall through a given discussion of the results gives practice in theuse of the logarithmic method of plotting, andincidentally the experiment illustrates the methodof recording the occurrence of an event by anelectric spark, and the method of estimating tenthsof an harmonic vibration. Apparatus.—The general arrangement of theapparatus is shown in Fig. 30. A is an electro-magnet placed on the wall about sixteen feetabove the floor. This when magnetized holds upa steel ball, which is relea
. Physical laboratory experiments : mechanics, optics and heat. the time requiredfor a body to fall through a given discussion of the results gives practice in theuse of the logarithmic method of plotting, andincidentally the experiment illustrates the methodof recording the occurrence of an event by anelectric spark, and the method of estimating tenthsof an harmonic vibration. Apparatus.—The general arrangement of theapparatus is shown in Fig. 30. A is an electro-magnet placed on the wall about sixteen feetabove the floor. This when magnetized holds upa steel ball, which is released on breaking the cir-cuit by a knife switch S. The ball in its descentBUPH falls through a trap B, which may be adjusted at any desiredC distance be- low A, thedistance ABbeing readoff on afixed box-wood scalegraduated trap Bis so constructed (see below), that a second circuitis broken the instant the ball passes apparatus for recording the interval of time elapsingbetween the breaking of the circuit at A and at B, consists. r=L LAW OF frp:ely falling bodies 109 first, of an induction coil C, the prinicary coil of which is con-nected in series first with A, and immediately afterward withB. When the circuit through A or 5 is broken, the currentinduced in the secondary of the coil causes a spark to passacross its terminals. These sparks are recorded in the man-ner described below on a revolving drum D. Since thesparks occur practically simultaneously with the releasing ofthe ball and the opening of the trap, a measurement of thetime interval between them gives the time desired. Thismethod of recording two events electrically has the greatadvantage that the simultaneously occurring secondary event,the sparking, can be made to occur at any place convenientfor measuring or recording, while the primary event itselfmay take place at any remote distance. The interval elapsing between two consecutive sparks maybe easily and accurately recorded as follo
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Keywords: ., bookcentury1900, bookde, booksubjectmechanics, booksubjectphysics
