താൾ:CiXIV132a.pdf/386

വിക്കിഗ്രന്ഥശാല സംരംഭത്തിൽ നിന്ന്
ഈ താളിൽ തെറ്റുതിരുത്തൽ വായന നടന്നിരിക്കുന്നു

LXXIV

the mirror falls AG as the chief ray and AC as any other incident
ray, A G is reflected in the direction of G A, A C in the direc
tion of CD. As A B and C L are parallel they are in one and
the same plane, hence also A C and C D. C D and A G being
in the same plane but not parallel, must intersect each other and as

△ A G C ≅ △ B G C
G B = G A

§ 186. As all the rays proceeding from a lighted body
would intersect only behind the plane of a perfectly polished
mirror, we would see only the images of the lighted objects but
not the mirror itself, but there is no perfectly polished surface.
A shining plane may be considered as consisting of infinite shin
ing points. Each of these points stirs up a whole system of
light-waves. This will cause an infinite number of waves, which
like sound-waves propagate themselves quite independent of
each other, only where they intersect one another will they
modify each other.

§ 187. An application of this is seen in the mirrors, by
which our image is produced. 363. Looking-glasses are plane
mirrors. The images produced by such mirrors are only
virtual images and stand as distant behind the mirror as the
object stands before it, 364. A thick piece of glass would show
two reflecting surfaces, hence looking-glasses should be as thin as
possible, 365; metallic mirrors at any rate will give one image.
In the same way we see the reversed image of houses, trees etc.
standing on the border of a river from the opposite bank.
Even in the glass of a window we may see our image under
certain circumstances. 368. Perfectly smooth, polished bodies
cannot be seen, 369—and absolutely non-reflecting bodies would
appear all equally black and could not be distinguished from
each other. Nevertheless black bodies are seen, why? Deep

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