... pencil of red light passed through a short-focus convex lens, L, Fig. 276 ; on intercepting it beyond Fig. 276. Diffraction. the focus of the lens, by means of an opaque ...

... a cylinder of lime be supported, as at L, Fig. 41, in the focus of the flame, its particles become heated to ...

... a cylinder of lime be supported, as at L (fig. 41), in the focus of the flame, its particles become heated to ...

... a cylinder of lime be supported, as at L (fig. 41), in the focus of the flame, its particles become heated to ...

... are parallel to the axis, and form no focus (Fig. 59). Fig. 61. If L continues to approach the mirror (Fig. 61), it ... principal focal distance. In ordinary lenses the principal focus coincides very ... rays diverge from L (Fig. 77). The angle of incidence is here greater ...

... double microscope, and is thus constructed: Let CD (fig. 12) represent a darkened chamber per- forated at L, where a convex lens is fixed, thecurvalure of whicli is such, that the focus of parallel rays falls upon the opposite wall. ...

... a point, F; which is the principal virtual focus. In the case in which the rays proceed from a point, L (fig. 390), on the axis, it is found by the same construction that a virtual focus is formed at /, which is between the principal ...

... This is explained by the diagram, fig. 78 ; l represents a convex lens of six Fig. 78. inches focus, upon which fall the two rays r r ...

... which this takes place will be understood by reference to fig. 26, where A B is an object placed beyond P, the principal focus of the aplanatic combination. From every point of ...

... on them, from each point of the object. Fig. 13, L represents a bi-convex lens; A B C, an arrow beyond 40 PHYSICAL OPTICS. the principal focus, with its point upwards. The rays A o ...