The London, Edinburgh and Dublin philosophical magazine and journal of science . H 2 and if t<\ ±6S Dr. W. F. (i. Swarm on the Electrical #-2, on cooling the film down to liquid-air temperature(-180° C.) we should have \_i80Ao = (273/93) 2 = 858, so thatthe distance of the bend from the origin of thickness shouldbe, at liquid-air temperature, 8*58 times its value at 0° 0. It was found that no such displacement of the bend tookplace, and apart from certain relatively small variations ofthe resistance of the films with temperature, which will bediscussed later, the curves at the two temperatu
The London, Edinburgh and Dublin philosophical magazine and journal of science . H 2 and if t<\ ±6S Dr. W. F. (i. Swarm on the Electrical #-2, on cooling the film down to liquid-air temperature(-180° C.) we should have \_i80Ao = (273/93) 2 = 858, so thatthe distance of the bend from the origin of thickness shouldbe, at liquid-air temperature, 8*58 times its value at 0° 0. It was found that no such displacement of the bend tookplace, and apart from certain relatively small variations ofthe resistance of the films with temperature, which will bediscussed later, the curves at the two temperatures werepractically coincident, at any rate in the neighbourhood ofthe bend. The experiments are not taken as necessarilyproving that \ does not vary as #~2, but rather as showingthat the explanation of the sharp bend is to be found fromanother standpoint than that which explains it as due to thethickness of the film becoming comparable with the meanfree path. It will be more convenient to discuss this pointafter the apparatus and experiments have been described. Fig-. M ^--rJUUUUUULL-| Apparatus and Experiments.—The films were deposited bysputtering from a platinum cathode in vacuo, and all thefilms corresponding to a single set were deposited in thesame vacuum. In this way a greater uniformity of the rateof deposition can be obtained than in the case where theapparatus is taken down after the deposition of each film,as in the experiments of Patterson. The apparatus isrepresented in fig. 1. The cathode C, which consisted of a piece of platinum foil Resistance of Thin Metallic Films. 469 2*5 cm. square, was fixed in a wide glass tube 4*5 cm. indiameter, which could be exhausted by means of an automaticpump. The top of the cathode was covered with mica. Theanode A passed down through the centre of a tap (the purposeof which will presently be described) and was fixed perma-nently in position in the wide tube. The ends of the apparatuscould be closed with glass plates B a
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
