. An elementary manual of radiotelegraphy and radiotelephony for students and operators . oscillations. A smallfragment of silvered glass attached tothe disc serves to reflect a ray of lightupon the scale and to indicate a move-ment of the disc. The average torque on the ringand therefore its deflecting moment isproportional to the square of the currentin the coil and to the square of thefrequency for the same , if the frequency is constant and the ring is suspendedby a quartz fibre of constant size and length, the restoring torquevaries as to the deflection, and the deflection
. An elementary manual of radiotelegraphy and radiotelephony for students and operators . oscillations. A smallfragment of silvered glass attached tothe disc serves to reflect a ray of lightupon the scale and to indicate a move-ment of the disc. The average torque on the ringand therefore its deflecting moment isproportional to the square of the currentin the coil and to the square of thefrequency for the same , if the frequency is constant and the ring is suspendedby a quartz fibre of constant size and length, the restoring torquevaries as to the deflection, and the deflection would measurethe mean square or integral value of the oscillations passingthrough the coils. This conclusion has been confirmed by Pierce experi-mentally. This form of detector, therefore, like the thermaldetectors, measures the integral value of the oscillations ; butsince the mechanical forces are small, such an electrodynamicdetector is not nearly as sensitive as the best forms of thermaldetector. Nevertheless, in some quantitative researches it hasproved itself to be very Fig. 22. OSCILLATION DETECTOKS 229 P. Mode of employing^ Oscillation Detectors in combinationwith Recording Instruments to detect Electric Waves. Incousiderin»» the above-described oscillation detectors it will beseen that, with the exception of the electrodynaniic detectora,tliey may all Ih3 divided into three classes— (1) Those which under tho action of electric oscillationsunder<.jo a change which in eilect is equivalent to an alterationof resistance. (2) Those which under the action of electric oscillationsundergo a change which induces an electromotive force inanother associated circuit. (3) Those which possess a unilateral conductivity, offeringtherefore a greater resistance to the passage of a curix*nt inone direction than in the opposite direction. As reganls the first class, viz. those which under theaction of electric oscillations undergo a change equivalent toa change in resista
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Keywords: ., bookcentury1900, bookdecade1910, booksubjecttelegra, bookyear1916
