An elementary treatise on optics / by I.W. Jackson.

  • Jackson, I. W. (Isaac Wilber), 1804-1877
Date:
1867
Catalogue details

Licence: Public Domain Mark

Credit: An elementary treatise on optics / by I.W. Jackson. Source: Wellcome Collection.

Provider: This material has been provided by the Francis A. Countway Library of Medicine, through the Medical Heritage Library. The original may be consulted at the Francis A. Countway Library of Medicine, Harvard Medical School.

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    I I : r I : I * andl' = q-f; s ; and hence or but hence This law is also a consequence of the wave-theory. It may not be unnecessary to remind the student, that the transmission is here supposed to take place in a vacuum. 15^ The intensity of the light received by a plane sur- face, placed obliquely to the direction of the rays, is pro- portional to the sine of the angle which their direction makes with the surface. Let the beam of light pp [Fig. 1] fall upon a plane surface be, at right angles to its direction : using the same notation as before, we have If now the surface be inclined so as to make with the direction of the rays any angle a, we have (denoting the surface in its new position by s', and the intensity by I'), r = % s' But be = dc. sin a; hence s = s'. sin a, and
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