This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 Excerpt: ... a constant ratio to the diameter of the wire) we alter its resistance in the ratio -: i. But the sensitiveness of the galvanometer, or the deflexion produced by a very small current, is proportional to the number of turns; it is therefore altered in the ratio n: i. Thus the sensitiveness is proportional to Vg. ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1894 Excerpt: ... a constant ratio to the diameter of the wire) we alter its resistance in the ratio -: i. But the sensitiveness of the galvanometer, or the deflexion produced by a very small current, is proportional to the number of turns; it is therefore altered in the ratio n: i. Thus the sensitiveness is proportional to Vg. Therefore the deflexion produced is proportional to P.sdpVg gs + 2)+q(r+s) This is a maximum for variations of g when p_q + s) nr _r(P + q). or-----j or--. s+q p + r This then is the best value for the galvanometer resistance. The winding of the galvanometer would not, as a rule, be made to have this value, but this shows us that if the arms are of high resistance it is best to use a galvanometer wound with fine wire; and if they are of low resistance, one wound with thick wire. If we arrange to give the above value to the galvanometer resistance we get G _ Psdp _ Pdp 2$r + s) 2(j + q) And the deflexion is proportional to PdpVr AP +?)P + r) From this it follows that, as far as this consideration alone is concerned, we should make q very small and r very large. 9. But the accuracy of the determination will depend upon two distinct considerations, (i) The sensitiveness and suitability of the galvanometer; (ii) The accuracy to which the adjustable resistances can be adjusted and read off. To consider the second of these; since the estimated value of p is given by we see that, if dq, dr, ds are errors made in reading the values of q, r, s, and dp is the corresponding error in the estimated value of p, supposing now that there is absolutely no current in the galvanometer, dp dq dr ds p q r s Therefore any relative error made in q, r, or s will produce an equal relative error in /. So that if we wish to measure / to the same absolute accuracy as...
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Seller's Description:
Very good No DJ. First Edition. A few pencil markings in book. Rebound by the library with burgundy buckram. No DJ. Library has this pencil notation: Gift of E.P. Lewis. E.P. Lewis was the head of the Physics Dept. at UC Berkeley from 1918 until his death in 1926. Usual library markings. 228pp.
