Laboratory exercises in physics for secondary schools (1902)
Twiss, George Ransom, b. 1863 · New York, London, The Macmillan company · leaf 165
Exercise 25, a relay and two more cells of battery are needed at eachstation. (5) The sameline wire may beused, but is sup-posed to be manymiles longer, sothat the additionalresistance makesthe current tooweak to operate the sounder. If the teacher desire,he may insert a suitable resistance to… … Fig. 37.—Telegraph Relay. MAGNETISM AND ELECTRICITY 137 (J) The other two are called the local circuit posts.Trace the metallic paths from them to the air gapbetween the platinum contact point on the lever andthat on the screw against which the lever strikeswhen the armature is attracted toward the…
Physics
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