A text-book of physics, largely experimentalOn the Harvard college "Descriptive list of elementary physical experiments." . Boston.—E. H. H. REDACTION OF LIGHT. 177 after it leaves the glass at 2. The line NNf, Fig. 120, is drawn nor-mal to the refracting surface at the point of emergence. From thispoint equal distances are laid off, to B and to C. Lines are drawnfrom B and from C to the line NN at right angles. CE -T- BD = the index of refraction from air to glass. EXERCISE 25 (21 in old list).INDEX OF REFRACTION OF WATER. Apparatus: Articles 3, 14, 15, 24A, 24s, 29, 30, and a sheet ofpaper a
A text-book of physics, largely experimentalOn the Harvard college "Descriptive list of elementary physical experiments." . Boston.—E. H. H. REDACTION OF LIGHT. 177 after it leaves the glass at 2. The line NNf, Fig. 120, is drawn nor-mal to the refracting surface at the point of emergence. From thispoint equal distances are laid off, to B and to C. Lines are drawnfrom B and from C to the line NN at right angles. CE -T- BD = the index of refraction from air to glass. EXERCISE 25 (21 in old list).INDEX OF REFRACTION OF WATER. Apparatus: Articles 3, 14, 15, 24A, 24s, 29, 30, and a sheet ofpaper about 6 inches square. Put the partition N in place, as shown m Fig. 121, and pour waterinto the jar until its surface comes within 1 or 2 mm. of the middletooth of the partition. Then by means of the plunger (No. 14), at-tached to the side of the jar by means of its clasp, raise the level ofthe water till the apparent distance between the middle tooth of thepartition and its reflection in the water surface is less than 1 mm.(To see this reflection well, one should look through the wall of theempty part of tne jar.). P d/~?&-. FIG. 121. FIG. 122. Then the brass index 6 is attached to the jar, as shown in Fig. 121,and is raised or lowered, with the tip p touching the glass, until aneye on the line Cg, 20 or 30 cm. from the jar, can barely see p, thevery tip of b, apparently in a straight line with Cg. This settingshould be made with care, and after it is made the experimentermust look to see whether the tooth at C is clear of the water. If itslowest edge touches the water the setting is useless, and all of theadjustments must be made anew before a reading is made. When all the adjustments have been successfully made, measure i78 PHYSICS. carefully the distance from the top of the jar down to the tip, p, ofthe index, the measuring-stick being kept outside the jar. Measure now the inside diameter of the jar. Measure also, unless it is already known, the distance * of Cbelow the t
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectphysics
